From e133737ffe864db87cdd7ef131c9b30cccc94300 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Josh=20Goldberg=20=E2=9C=A8?= <git@joshuakgoldberg.com>
Date: Mon, 13 Nov 2023 00:51:37 -0500
Subject: [PATCH] Throw better exception when failing to load plugin (#447)

Co-authored-by: Bryan Mishkin <698306+bmish@users.noreply.github.com>
---
 lib/package-json.ts           | 6 ++++--
 test/lib/generate/cjs-test.ts | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/package-json.ts b/lib/package-json.ts
index 4beb6c80..1b328d60 100644
--- a/lib/package-json.ts
+++ b/lib/package-json.ts
@@ -36,7 +36,7 @@ export async function loadPlugin(path: string): Promise<Plugin> {
   try {
     // Try require first which should work for CJS plugins.
     return require(pluginRoot) as Plugin; // eslint-disable-line import/no-dynamic-require
-  } catch {
+  } catch (error) {
     // Otherwise, for ESM plugins, we'll have to try to resolve the exact plugin entry point and import it.
     const pluginPackageJson = loadPackageJson(path);
     let pluginEntryPoint;
@@ -61,8 +61,10 @@ export async function loadPlugin(path: string): Promise<Plugin> {
       }
     }
 
+    // If the ESM export doesn't exist, fall back to throwing the CJS error
+    // (if the ESM export does exist, we'll validate it next)
     if (!pluginEntryPoint) {
-      throw new Error('Unable to determine plugin entry point.');
+      throw error;
     }
 
     const pluginEntryPointAbs = join(pluginRoot, pluginEntryPoint);
diff --git a/test/lib/generate/cjs-test.ts b/test/lib/generate/cjs-test.ts
index 88eb1a2f..577e6ccd 100644
--- a/test/lib/generate/cjs-test.ts
+++ b/test/lib/generate/cjs-test.ts
@@ -68,7 +68,7 @@ describe('generate (cjs)', function () {
         'cjs-main-file-does-not-exist'
       );
       await expect(generate(FIXTURE_PATH)).rejects.toThrow(
-        'Unable to determine plugin entry point.'
+        /Cannot find module/u
       );
     });
   });