FIX: Pass fileName to error handler for media optimization (#14058)

The file name is used to look up the promise to resolve; it
was being passed for the successful path but not for the
error path.

public/javascripts/media-optimization-worker.js

@@ -139,7 +139,8 @@ onmessage = async function (e) {
         console.error(error);
         postMessage({
           type: "error",
-          file: e.data.file
+          file: e.data.file,
+          fileName: e.data.fileName
         });
       }
       break;