Improved image upload error handling and fixed bad user-avatar rewriting

+<?php namespace BookStack\Exceptions;
+
+
+use Exception;
+
+class ImageUploadException extends Exception {}
\ No newline at end of file

@@ -2,6 +2,7 @@
 
 namespace BookStack\Http\Controllers;
 
+use BookStack\Exceptions\ImageUploadException;
 use BookStack\Repos\ImageRepo;
 use Illuminate\Filesystem\Filesystem as File;
 use Illuminate\Http\Request;
@@ -69,7 +70,13 @@ class ImageController extends Controller
         ]);
 
         $imageUpload = $request->file('file');
-        $image = $this->imageRepo->saveNew($imageUpload, $type);
+
+        try {
+            $image = $this->imageRepo->saveNew($imageUpload, $type);
+        } catch (ImageUploadException $e) {
+            return response($e->getMessage(), 500);
+        }
+
         return response()->json($image);
     }
 

@@ -56,6 +56,7 @@ module.exports = function (ngApp) {
                 var usingIds = typeof scope.currentId !== 'undefined' || scope.currentId === 'false';
                 scope.image = scope.currentImage;
                 scope.value = scope.currentImage || '';
+                if (usingIds) scope.value = scope.currentId;
 
                 function setImage(imageModel, imageUrl) {
                     scope.image = imageUrl;