errors from uploading data are forwarded to GUI

frontend-js/src/main/js/gui/leftPanel/OverlayPanel.js

@@ -8,6 +8,9 @@ var PanelControlElementType = require('../PanelControlElementType');
 var GuiConnector = require('../../GuiConnector');
 var logger = require('../../logger');
 var Functions = require('../../Functions');
+var NetworkError = require('../../NetworkError');
+
+var HttpStatus = require('http-status-codes');
 
 function OverlayPanel(params) {
   params.panelName = "overlays";
@@ -446,6 +449,16 @@ OverlayPanel.prototype.openAddOverlayDialog = function() {
           return self.refresh();
         }).then(function() {
           $(dialog).dialog("close");
+        }, function(error) {
+          if (error instanceof NetworkError) {
+            if (error.statusCode === HttpStatus.BAD_REQUEST) {
+              GuiConnector.alert("Problematic input: <br/>" + error.content);
+            } else {
+              throw error;
+            }
+          } else {
+            throw error;
+          }
         });
       }
     }