Don't pipe mp3.js through babel, add respack fetch error

gulpfile.js

@@ -32,7 +32,6 @@ gulp.task('css', function(){
 
 gulp.task("mp3", function () {
   return gulp.src("src/js/mp3/*.js")
-    .pipe(babel())
     .pipe(uglify())
     .pipe(concat("mp3-min.js"))
     .pipe(gulp.dest("lib"));

src/js/ResourcePack.js

@@ -104,7 +104,7 @@ Respack.prototype.getBlob = function(url, progress) {
             resolve(req.response);
         };
         req.onerror = function() {
-            reject(Error("Could not load respack at URL" + url));
+            reject(Error("Could not fetch respack at URL" + url));
         };
         req.onprogress = event => {
             if (event.lengthComputable) {
@@ -117,6 +117,9 @@ Respack.prototype.getBlob = function(url, progress) {
             }
         };
         req.send();
+    }).catch(error => {
+        // Infinitely more useful than the error Same Origin gives
+        throw Error("Could not fetch respack at URL" + url);
     });
 }