Merge pull request #807 from fredj/mouse-position

Don't attempt to display the mouse position if the frameState is null

src/ol/control/mousepositioncontrol.js

@@ -230,7 +230,7 @@ goog.exportProperty(
  */
 ol.control.MousePosition.prototype.updateHTML_ = function(pixel) {
   var html = this.undefinedHTML_;
-  if (!goog.isNull(pixel)) {
+  if (!goog.isNull(pixel) && !goog.isNull(this.mapProjection_)) {
     if (goog.isNull(this.transform_)) {
       var projection = this.getProjection();
       if (goog.isDef(projection)) {