Improved error handling for file uploads

src/web/InputWaiter.js

@@ -214,6 +214,10 @@ InputWaiter.prototype.handleLoaderMessage = function(e) {
         fileLoaded.textContent = r.progress + "%";
     }
 
+    if (r.hasOwnProperty("error")) {
+        this.app.alert(r.error, "danger", 10000);
+    }
+
     if (r.hasOwnProperty("fileBuffer")) {
         log.debug("Input file loaded");
         this.fileBuffer = r.fileBuffer;

src/web/LoaderWorker.js

@@ -46,5 +46,9 @@ self.loadFile = function(file) {
         seek();
     };
 
+    reader.onerror = function(e) {
+        self.postMessage({"error": file.error.message});
+    };
+
     seek();
 };