From b3c5896623a85af2960802fc4fd624f2e25ecf07 Mon Sep 17 00:00:00 2001
From: Connor Clark <cjamcl@google.com>
Date: Tue, 10 Mar 2020 14:08:15 -0700
Subject: [PATCH 1/6] core(js-bundles): return error object when sizes cannot
 be determined

---
 .../byte-efficiency/unused-javascript.js      |  4 +++-
 lighthouse-core/computed/js-bundles.js        | 20 +++++++++----------
 .../computed/module-duplication.js            |  2 ++
 .../test/computed/js-bundles-test.js          |  8 ++------
 types/artifacts.d.ts                          |  2 +-
 5 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/lighthouse-core/audits/byte-efficiency/unused-javascript.js b/lighthouse-core/audits/byte-efficiency/unused-javascript.js
index 1ff94e71eaae..073ba476aef8 100644
--- a/lighthouse-core/audits/byte-efficiency/unused-javascript.js
+++ b/lighthouse-core/audits/byte-efficiency/unused-javascript.js
@@ -115,6 +115,8 @@ class UnusedJavaScript extends ByteEfficiencyAudit {
    */
   static createBundleMultiData(item, wasteData, bundle, lengths, bundleSourceUnusedThreshold) {
     if (!bundle.script.content) return;
+    const sizes = bundle.sizes;
+    if ('error' in sizes) return;
 
     /** @type {Record<string, number>} */
     const files = {};
@@ -151,7 +153,7 @@ class UnusedJavaScript extends ByteEfficiencyAudit {
       .sort(([_, unusedBytes1], [__, unusedBytes2]) => unusedBytes2 - unusedBytes1)
       .slice(0, 5)
       .map(([key, unusedBytes]) => {
-        const total = key === '(unmapped)' ? bundle.sizes.unmappedBytes : bundle.sizes.files[key];
+        const total = key === '(unmapped)' ? sizes.unmappedBytes : sizes.files[key];
         return {
           key,
           unused: Math.round(unusedBytes * transferRatio),
diff --git a/lighthouse-core/computed/js-bundles.js b/lighthouse-core/computed/js-bundles.js
index 6ee004a2376d..c839eeeb072a 100644
--- a/lighthouse-core/computed/js-bundles.js
+++ b/lighthouse-core/computed/js-bundles.js
@@ -22,10 +22,6 @@ function computeGeneratedFileSizes(map, content) {
   const totalBytes = content.length;
   let unmappedBytes = totalBytes;
 
-  // If the map + contents don't line up, return a result that
-  // denotes nothing is mapped.
-  const failureResult = {files: {}, unmappedBytes, totalBytes};
-
   // @ts-ignore: This function is added in SDK.js. This will eventually be added to CDT.
   map.computeLastGeneratedColumns();
 
@@ -44,22 +40,24 @@ function computeGeneratedFileSizes(map, content) {
 
     const line = lines[lineNum];
     if (line === null) {
-      log.error('JSBundles', `${map.url()} mapping for line out of bounds: ${lineNum + 1}`);
-      return failureResult;
+      const error = `${map.url()} mapping for line out of bounds: ${lineNum + 1}`;
+      log.error('JSBundles', error);
+      return {error};
     }
 
     if (colNum > line.length) {
-      // eslint-disable-next-line max-len
-      log.error('JSBundles', `${map.url()} mapping for column out of bounds: ${lineNum + 1}:${colNum}`);
-      return failureResult;
+      const error = `${map.url()} mapping for column out of bounds: ${lineNum + 1}:${colNum}`;
+      log.error('JSBundles', error);
+      return {error};
     }
 
     let mappingLength = 0;
     if (lastColNum !== undefined) {
       if (lastColNum > line.length) {
         // eslint-disable-next-line max-len
-        log.error('JSBundles', `${map.url()} mapping for last column out of bounds: ${lineNum + 1}:${lastColNum}`);
-        return failureResult;
+        const error = `${map.url()} mapping for last column out of bounds: ${lineNum + 1}:${lastColNum}`;
+        log.error('JSBundles', error);
+        return {error};
       }
       mappingLength = lastColNum - colNum;
     } else {
diff --git a/lighthouse-core/computed/module-duplication.js b/lighthouse-core/computed/module-duplication.js
index 69bc2d949273..bdbc001d0abb 100644
--- a/lighthouse-core/computed/module-duplication.js
+++ b/lighthouse-core/computed/module-duplication.js
@@ -57,6 +57,8 @@ class ModuleDuplication {
 
     // Determine size of each `sources` entry.
     for (const {rawMap, sizes} of bundles) {
+      if ('error' in sizes) continue;
+
       /** @type {SourceData[]} */
       const sourceDataArray = [];
       sourceDatasMap.set(rawMap, sourceDataArray);
diff --git a/lighthouse-core/test/computed/js-bundles-test.js b/lighthouse-core/test/computed/js-bundles-test.js
index 702c58f65575..a71d28b9d6fc 100644
--- a/lighthouse-core/test/computed/js-bundles-test.js
+++ b/lighthouse-core/test/computed/js-bundles-test.js
@@ -292,9 +292,7 @@ describe('JSBundles computed artifact', () => {
             "sourceURL": "src/foo.js",
           },
           "sizes": Object {
-            "files": Object {},
-            "totalBytes": 13,
-            "unmappedBytes": 13,
+            "error": "compiled.js.map mapping for last column out of bounds: 1:14",
           },
         }
       `);
@@ -314,9 +312,7 @@ describe('JSBundles computed artifact', () => {
             "sourceURL": "src/foo.js",
           },
           "sizes": Object {
-            "files": Object {},
-            "totalBytes": 0,
-            "unmappedBytes": 0,
+            "error": "compiled.js.map mapping for column out of bounds: 1:1",
           },
         }
       `);
diff --git a/types/artifacts.d.ts b/types/artifacts.d.ts
index a5ca7517f793..a0ca1c14abb8 100644
--- a/types/artifacts.d.ts
+++ b/types/artifacts.d.ts
@@ -307,7 +307,7 @@ declare global {
           files: Record<string, number>;
           unmappedBytes: number;
           totalBytes: number;
-        };
+        } | {error: string};
       }
 
       /** @see https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#Attributes */

From d517ec5aad15b6ed8115da340b75be7cff8b5f0e Mon Sep 17 00:00:00 2001
From: Connor Clark <cjamcl@google.com>
Date: Mon, 28 Sep 2020 15:17:43 -0500
Subject: [PATCH 2/6] add test for coverage

---
 .../test/computed/js-bundles-test.js          | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/lighthouse-core/test/computed/js-bundles-test.js b/lighthouse-core/test/computed/js-bundles-test.js
index 4a4019c77a7b..53ed74377dc4 100644
--- a/lighthouse-core/test/computed/js-bundles-test.js
+++ b/lighthouse-core/test/computed/js-bundles-test.js
@@ -343,5 +343,30 @@ describe('JsBundles computed artifact', () => {
         }
       `);
     });
+
+    it('5', async () => {
+      const newMappings = map.mappings.split(',');
+      expect(newMappings[1]).toBe('SAAAA');
+      // Make the line offset very big, force out of bounds.
+      // See https://www.mattzeunert.com/2016/02/14/how-do-source-maps-work.html
+      newMappings[1] = 'kDAAAA';
+      map.mappings = newMappings.join(',');
+      expect(await test()).toMatchInlineSnapshot(`
+        Object {
+          "entry": SourceMapEntry {
+            "columnNumber": 642,
+            "lastColumnNumber": 651,
+            "lineNumber": 0,
+            "name": undefined,
+            "sourceColumnNumber": 18,
+            "sourceLineNumber": 1,
+            "sourceURL": "src/foo.js",
+          },
+          "sizes": Object {
+            "error": "compiled.js.map mapping for last column out of bounds: 1:685",
+          },
+        }
+      `);
+    });
   });
 });

From 5014757e223a8e6a18a5cae36137986b1ad9894d Mon Sep 17 00:00:00 2001
From: Connor Clark <cjamcl@google.com>
Date: Thu, 1 Oct 2020 16:20:07 -0500
Subject: [PATCH 3/6] Update
 lighthouse-core/audits/byte-efficiency/unused-javascript.js

Co-authored-by: Brendan Kenny <bckenny@gmail.com>
---
 lighthouse-core/audits/byte-efficiency/unused-javascript.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lighthouse-core/audits/byte-efficiency/unused-javascript.js b/lighthouse-core/audits/byte-efficiency/unused-javascript.js
index 8c09a538f7d0..5b3832b2a2ae 100644
--- a/lighthouse-core/audits/byte-efficiency/unused-javascript.js
+++ b/lighthouse-core/audits/byte-efficiency/unused-javascript.js
@@ -106,7 +106,7 @@ class UnusedJavaScript extends ByteEfficiencyAudit {
       if (item.wastedBytes <= unusedThreshold) continue;
       items.push(item);
 
-      // If there was an error calculated the bundle sizes, we can't
+      // If there was an error calculating the bundle sizes, we can't
       // create any sub-items.
       if (!bundle || 'error' in bundle.sizes) continue;
       const sizes = bundle.sizes;

From f4bfbda98861c5dce73cf13c1a573594bbef4812 Mon Sep 17 00:00:00 2001
From: Connor Clark <cjamcl@google.com>
Date: Thu, 1 Oct 2020 17:14:58 -0500
Subject: [PATCH 4/6] error message

---
 lighthouse-core/computed/js-bundles.js        | 22 ++++++++++---------
 .../create-polyfill-size-estimation.js        |  2 +-
 .../test/computed/js-bundles-test.js          | 22 ++++++++++++++++---
 types/artifacts.d.ts                          |  2 +-
 4 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/lighthouse-core/computed/js-bundles.js b/lighthouse-core/computed/js-bundles.js
index b97a7cbaf931..9f836fb1a13f 100644
--- a/lighthouse-core/computed/js-bundles.js
+++ b/lighthouse-core/computed/js-bundles.js
@@ -39,25 +39,27 @@ function computeGeneratedFileSizes(map, content) {
     // Lines and columns are zero-based indices. Visually, lines are shown as a 1-based index.
 
     const line = lines[lineNum];
-    if (line === null) {
-      const error = `${map.url()} mapping for line out of bounds: ${lineNum + 1}`;
-      log.error('JSBundles', error);
-      return {error};
+    if (line === null || line === undefined) {
+      const errorMessage = `${map.url()} mapping for line out of bounds: ${lineNum + 1}`;
+      log.error('JSBundles', errorMessage);
+      return {errorMessage};
     }
 
     if (colNum > line.length) {
-      const error = `${map.url()} mapping for column out of bounds: ${lineNum + 1}:${colNum}`;
-      log.error('JSBundles', error);
-      return {error};
+      const errorMessage =
+        `${map.url()} mapping for column out of bounds: ${lineNum + 1}:${colNum}`;
+      log.error('JSBundles', errorMessage);
+      return {errorMessage};
     }
 
     let mappingLength = 0;
     if (lastColNum !== undefined) {
       if (lastColNum > line.length) {
         // eslint-disable-next-line max-len
-        const error = `${map.url()} mapping for last column out of bounds: ${lineNum + 1}:${lastColNum}`;
-        log.error('JSBundles', error);
-        return {error};
+        const errorMessage =
+          `${map.url()} mapping for last column out of bounds: ${lineNum + 1}:${lastColNum}`;
+        log.error('JSBundles', errorMessage);
+        return {errorMessage};
       }
       mappingLength = lastColNum - colNum;
     } else {
diff --git a/lighthouse-core/scripts/legacy-javascript/create-polyfill-size-estimation.js b/lighthouse-core/scripts/legacy-javascript/create-polyfill-size-estimation.js
index d60a796b732d..cfea478e1185 100644
--- a/lighthouse-core/scripts/legacy-javascript/create-polyfill-size-estimation.js
+++ b/lighthouse-core/scripts/legacy-javascript/create-polyfill-size-estimation.js
@@ -88,7 +88,7 @@ async function main() {
     SourceMaps: [{scriptUrl: '', map: bundleMap}],
   };
   const bundles = await JsBundles.compute_(artifacts);
-  if ('error' in bundles[0].sizes) throw new Error(bundles[0].sizes.error);
+  if ('errorMessage' in bundles[0].sizes) throw new Error(bundles[0].sizes.errorMessage);
   const bundleFileSizes = bundles[0].sizes.files;
 
   const allModules = Object.keys(bundleFileSizes).filter(s => s.startsWith('node_modules'));
diff --git a/lighthouse-core/test/computed/js-bundles-test.js b/lighthouse-core/test/computed/js-bundles-test.js
index 53ed74377dc4..5aeafbdc0e67 100644
--- a/lighthouse-core/test/computed/js-bundles-test.js
+++ b/lighthouse-core/test/computed/js-bundles-test.js
@@ -344,12 +344,12 @@ describe('JsBundles computed artifact', () => {
       `);
     });
 
-    it('5', async () => {
+    it('emits error when column out of bounds', async () => {
       const newMappings = map.mappings.split(',');
       expect(newMappings[1]).toBe('SAAAA');
-      // Make the line offset very big, force out of bounds.
+      // Make the column offset very big, force out of bounds.
       // See https://www.mattzeunert.com/2016/02/14/how-do-source-maps-work.html
-      newMappings[1] = 'kDAAAA';
+      newMappings[1] = 'kD' + 'AAAA';
       map.mappings = newMappings.join(',');
       expect(await test()).toMatchInlineSnapshot(`
         Object {
@@ -368,5 +368,21 @@ describe('JsBundles computed artifact', () => {
         }
       `);
     });
+
+    it('emits error when line out of bounds', async () => {
+      const newMappings = map.mappings.split(',');
+      expect(newMappings[1]).toBe('SAAAA');
+      // Make the line offset very big, force out of bounds.
+      // See https://sourcemaps.info/spec.html#:~:text=broken%20down%20as%20follows
+      map.mappings = ';'.repeat(10) + map.mappings;
+      expect(await test()).toMatchInlineSnapshot(`
+        Object {
+          "entry": null,
+          "sizes": Object {
+            "error": "compiled.js.map mapping for line out of bounds: 11",
+          },
+        }
+      `);
+    });
   });
 });
diff --git a/types/artifacts.d.ts b/types/artifacts.d.ts
index 936da14ee3c3..ee59a7a299b6 100644
--- a/types/artifacts.d.ts
+++ b/types/artifacts.d.ts
@@ -326,7 +326,7 @@ declare global {
           files: Record<string, number>;
           unmappedBytes: number;
           totalBytes: number;
-        } | {error: string};
+        } | {errorMessage: string};
       }
 
       /** @see https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#Attributes */

From a7c98acf52c6d74657985d4cb334e5f332a92610 Mon Sep 17 00:00:00 2001
From: Connor Clark <cjamcl@google.com>
Date: Thu, 1 Oct 2020 17:47:42 -0500
Subject: [PATCH 5/6] tsc

---
 lighthouse-core/audits/byte-efficiency/unused-javascript.js | 2 +-
 lighthouse-core/computed/module-duplication.js              | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/lighthouse-core/audits/byte-efficiency/unused-javascript.js b/lighthouse-core/audits/byte-efficiency/unused-javascript.js
index 5b3832b2a2ae..0b031864cd63 100644
--- a/lighthouse-core/audits/byte-efficiency/unused-javascript.js
+++ b/lighthouse-core/audits/byte-efficiency/unused-javascript.js
@@ -108,7 +108,7 @@ class UnusedJavaScript extends ByteEfficiencyAudit {
 
       // If there was an error calculating the bundle sizes, we can't
       // create any sub-items.
-      if (!bundle || 'error' in bundle.sizes) continue;
+      if (!bundle || 'errorMessage' in bundle.sizes) continue;
       const sizes = bundle.sizes;
 
       // Augment with bundle data.
diff --git a/lighthouse-core/computed/module-duplication.js b/lighthouse-core/computed/module-duplication.js
index 6222293eb312..73b974868893 100644
--- a/lighthouse-core/computed/module-duplication.js
+++ b/lighthouse-core/computed/module-duplication.js
@@ -91,7 +91,7 @@ class ModuleDuplication {
 
     // Determine size of each `sources` entry.
     for (const {rawMap, sizes} of bundles) {
-      if ('error' in sizes) continue;
+      if ('errorMessage' in sizes) continue;
 
       /** @type {SourceData[]} */
       const sourceDataArray = [];

From 6732fb3907b81dcc32092169835708e08a3df795 Mon Sep 17 00:00:00 2001
From: Connor Clark <cjamcl@google.com>
Date: Fri, 2 Oct 2020 15:31:07 -0500
Subject: [PATCH 6/6] update

---
 lighthouse-core/test/computed/js-bundles-test.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lighthouse-core/test/computed/js-bundles-test.js b/lighthouse-core/test/computed/js-bundles-test.js
index 5aeafbdc0e67..7a68b0f48907 100644
--- a/lighthouse-core/test/computed/js-bundles-test.js
+++ b/lighthouse-core/test/computed/js-bundles-test.js
@@ -292,7 +292,7 @@ describe('JsBundles computed artifact', () => {
             "sourceURL": "src/foo.js",
           },
           "sizes": Object {
-            "error": "compiled.js.map mapping for last column out of bounds: 1:14",
+            "errorMessage": "compiled.js.map mapping for last column out of bounds: 1:14",
           },
         }
       `);
@@ -312,7 +312,7 @@ describe('JsBundles computed artifact', () => {
             "sourceURL": "src/foo.js",
           },
           "sizes": Object {
-            "error": "compiled.js.map mapping for column out of bounds: 1:1",
+            "errorMessage": "compiled.js.map mapping for column out of bounds: 1:1",
           },
         }
       `);
@@ -363,7 +363,7 @@ describe('JsBundles computed artifact', () => {
             "sourceURL": "src/foo.js",
           },
           "sizes": Object {
-            "error": "compiled.js.map mapping for last column out of bounds: 1:685",
+            "errorMessage": "compiled.js.map mapping for last column out of bounds: 1:685",
           },
         }
       `);
@@ -379,7 +379,7 @@ describe('JsBundles computed artifact', () => {
         Object {
           "entry": null,
           "sizes": Object {
-            "error": "compiled.js.map mapping for line out of bounds: 11",
+            "errorMessage": "compiled.js.map mapping for line out of bounds: 11",
           },
         }
       `);