fix: handle empty content-type header (#9)

package.json

@@ -18,25 +18,25 @@
     "dev": "cd example && netlify dev"
   },
   "dependencies": {
-    "@netlify/functions": "^0.7.2",
+    "@netlify/functions": "^1.0.0",
     "etag": "^1.8.1",
     "fs-extra": "^10.0.0",
     "ipx": "^0.9.4",
     "mkdirp": "^1.0.4",
     "murmurhash": "^2.0.0",
     "node-fetch": "^2.0.0",
-    "ufo": "^0.7.10",
+    "ufo": "^0.7.11",
     "unstorage": "^0.2.8"
   },
   "devDependencies": {
     "@netlify/ipx": "link:.",
     "@nuxtjs/eslint-config-typescript": "^6.0.1",
     "@types/etag": "^1.8.1",
-    "@types/fs-extra": "^9.0.12",
-    "@types/node-fetch": "^2.0.0",
+    "@types/fs-extra": "^9.0.13",
+    "@types/node-fetch": "^2.6.1",
     "eslint": "^7.29.0",
-    "jiti": "^1.10.1",
+    "jiti": "^1.13.0",
     "standard-version": "^9.3.0",
-    "typescript": "^4.4.3"
+    "typescript": "^4.6.2"
   }
 }

src/http.ts

@@ -107,12 +107,15 @@ export async function loadSourceImage ({ cacheDir, url, requestEtag, modifiers,
     return {
       response: {
         statusCode: isLocal ? response.status : GATEWAY_ERROR,
-        body: `Source image server responsed with ${response.status} ${response.statusText}`
+        body: `Source image server responsed with ${response.status} ${response.statusText}`,
+        headers: {
+          'Content-Type': 'text/plain'
+        }
       }
     }
   }
-
-  if (!response.headers.get('content-type').startsWith('image/')) {
+  const contentType = response.headers.get('content-type')
+  if (contentType && !contentType.startsWith('image/')) {
     return {
       response: {
         statusCode: GATEWAY_ERROR,