google maps without background had some issues

CHANGELOG

@@ -9,6 +9,8 @@ minerva (15.1.1) stable; urgency=medium
     example P0C2L1)  could crash caching (#1377)
   * Bug fix: removing non-existing project results in warning not an error
     message (#1367)
+  * Bug fix: opening map in google maps without background resulted in
+    unexpected error (#1416)
 
  -- Piotr Gawron <piotr.gawron@uni.lu>  Thu, 23 Nov 2020 15:00:00 +0200
 

frontend-js/src/main/js/map/canvas/GoogleMaps/GoogleMapsApiCanvas.js

@@ -136,7 +136,11 @@ GoogleMapsApiCanvas.prototype.setupBackgroundOverlays = function (backgroundOver
     var mapType = new google.maps.ImageMapType(typeOptions);
     this.getGoogleMap().mapTypes.set(overlay.id.toString(), mapType);
   }
-  this.getGoogleMap().setMapTypeId(backgroundOverlays[0].id.toString());
+  if (backgroundOverlays[0] !== undefined) {
+    this.getGoogleMap().setMapTypeId(backgroundOverlays[0].id.toString());
+  } else {
+    this.getGoogleMap().setMapTypeId('none');
+  }
 };
 
 /**

frontend-js/src/test/js/map/canvas/GoogleMaps/GoogleMapsApiCanvas-test.js

@@ -58,6 +58,20 @@ describe('GoogleMapsApiCanvas', function () {
       assert.ok(result);
 
     });
+    it("no background overlays", function () {
+      var options = {
+        center: new Point(0, 0),
+        tileSize: 256,
+        width: 300,
+        height: 600,
+        minZoom: 2,
+        zoom: 5,
+        backgroundOverlays: []
+      };
+
+      var canvas = new GoogleMapsApiCanvas(testDiv, options);
+      assert.ok(canvas);
+    });
     it("getTileUrl", function () {
       var coordinates = {x: 0, y: 0};
       var canvas = new GoogleMapsApiCanvas(testDiv, testOptions);