[NRRPLT-7962] Added error propagation mechanism from opensim to frontend

Merged in NRRPLT-7962 (pull request #41)

- New subscriber for the ~/error topic
- Functionality that checks whether the error is coming from opensim
  mesh handling and propagates the error to the frontend

Approved-by: Stefano Nardo
Approved-by: Sandro Weber

gz3d/src/gziface.js

@@ -158,6 +158,25 @@ GZ3D.GZIface.prototype.onConnected = function() {
   };
   this.statusTopic.subscribe(statusUpdate.bind(this));
 
+  this.errorTopic = new ROSLIB.Topic({
+    ros: this.webSocket,
+    name: '~/error',
+    messageType: 'error'
+  });
+
+  var errorUpdate = function (message) {
+    // error with id 1 means that opensim faied to load a mesh
+    if (message.id === 1) {
+      this.emitter.emit('opensimMeshError', message);
+    }
+    // generic gazebo error handling
+    else {
+      console.error(`Error received from gazebo: ${message}`);
+    }
+  };
+
+  this.errorTopic.subscribe(errorUpdate.bind(this));
+
   this.materialTopic = new ROSLIB.Topic({
     ros: this.webSocket,
     name: '~/material',

gz3d/src/gzsdfparser.js

@@ -51,6 +51,11 @@ GZ3D.SdfParser.prototype.init = function() {
       that.onConnectionError();
     }
   });
+
+  this.gziface.emitter.on('opensimMeshError', function (error) {
+    that.gui.guiEvents.emit('opensimMeshError', error, 5000);
+    that.onConnectionError();
+  });
 };
 
 /**