fix: Fallback to parentLoad if parsing fails

hook.js

@@ -246,14 +246,16 @@ function createHook (meta) {
   async function getSource (url, context, parentGetSource) {
     if (hasIitm(url)) {
       const realUrl = deleteIitm(url)
-      const setters = await processModule({
-        srcUrl: realUrl,
-        context,
-        parentGetSource,
-        parentResolve: cachedResolve
-      })
-      return {
-        source: `
+
+      try {
+        const setters = await processModule({
+          srcUrl: realUrl,
+          context,
+          parentGetSource,
+          parentResolve: cachedResolve
+        })
+        return {
+          source: `
 import { register } from '${iitmURL}'
 import * as namespace from ${JSON.stringify(realUrl)}
 
@@ -268,6 +270,25 @@ ${Array.from(setters.values()).join('\n')}
 
 register(${JSON.stringify(realUrl)}, _, set, ${JSON.stringify(specifiers.get(realUrl))})
 `
+        }
+      } catch (cause) {
+        // If there are other ESM loader hooks registered as well as iitm,
+        // depending on the order they are registered, source might not be
+        // JavaScript.
+        //
+        // If we fail to parse a module for exports, we should fall back to the
+        // parent loader. These modules will not be wrapped with proxies and
+        // cannot be Hook'ed but at least this does not take down the entire app
+        // and block iitm from being used.
+        //
+        // We log the error because there might be bugs in iitm and without this
+        // it would be very tricky to debug
+        const err = new Error(`'import-in-the-middle' failed to wrap '${realUrl}'`)
+        err.cause = cause
+        console.warn(err)
+
+        // Revert back to the non-iitm URL
+        url = realUrl
       }
     }