Fixed console error message appearing while editing execution/required files (trying to diff)

amd/src/vplidefile.js

@@ -361,16 +361,18 @@ define(['jquery',
                     data: { id : current_id_vpl, name: fileName, val : editor.getValue() }
                 })
                 .done(function( result ) {
-                    var diffData = result.response.diff;
-                    var modified = 'ace-changed'; // CSS class.
-                    diffData.forEach(function(diff){
-                        if(diff.type != "=") {
-                            editor.session.removeGutterDecoration(diff.ln2-1, modified);
-                            editor.session.addGutterDecoration(diff.ln2-1, modified);
-                        } else {
-                            editor.session.removeGutterDecoration(diff.ln2-1, modified);
-                        }
-                    });
+                    if (result.success) {
+                        var diffData = result.response.diff;
+                        var modified = 'ace-changed'; // CSS class.
+                        diffData.forEach(function(diff){
+                            if(diff.type != "=") {
+                                editor.session.removeGutterDecoration(diff.ln2-1, modified);
+                                editor.session.addGutterDecoration(diff.ln2-1, modified);
+                            } else {
+                                editor.session.removeGutterDecoration(diff.ln2-1, modified);
+                            }
+                        });
+                    }
                 });
             };