work around a dreaded FF NS_ERROR_FAILURE for supporting retina

it’s a terrible and ugly hack with who-knows-which side-effects. I hate
computers.

history.txt

@@ -3130,3 +3130,7 @@ http://snap.berkeley.edu/run#cloud:Username=jens&ProjectName=rotation
 161123
 ------
 * Blocks, Morphic: “Undrop / Redrop” support for sticky comments
+
+161124
+------
+* Morphic, Store: work around a dreaded FF NS_ERROR_FAILURE for supporting retina

morphic.js

@@ -1103,7 +1103,7 @@
 
 /*global window, HTMLCanvasElement, FileReader, Audio, FileList*/
 
-var morphicVersion = '2016-November-23';
+var morphicVersion = '2016-November-24';
 var modules = {}; // keep track of additional loaded modules
 var useBlurredShadows = getBlurredShadowSupport(); // check for Chrome-bug
 
@@ -1508,9 +1508,9 @@ function enableRetinaSupport() {
             return this._isRetinaEnabled;
         },
         set: function(enabled) {
-            var prevPixelRatio = getPixelRatio(this);
-            var prevWidth = this.width;
-            var prevHeight = this.height;
+            var prevPixelRatio = getPixelRatio(this),
+                prevWidth = this.width,
+                prevHeight = this.height;
 
             this._isRetinaEnabled = enabled;
             if (getPixelRatio(this) != prevPixelRatio) {
@@ -1526,12 +1526,19 @@ function enableRetinaSupport() {
             return uber.width.get.call(this) / getPixelRatio(this);
         },
         set: function(width) {
-            var pixelRatio = getPixelRatio(this);
-            uber.width.set.call(this, width * pixelRatio);
-            var context = this.getContext('2d');
-            context.restore();
-            context.save();
-            context.scale(pixelRatio, pixelRatio);
+            try { // workaround one of FF's dreaded NS_ERROR_FAILURE bugs
+                // this should be taken out as soon as FF gets fixed again
+                var pixelRatio = getPixelRatio(this),
+                    context;
+                uber.width.set.call(this, width * pixelRatio);
+                context = this.getContext('2d');
+                context.restore();
+                context.save();
+                context.scale(pixelRatio, pixelRatio);
+            } catch (err) {
+                console.log('Retina Display Support Problem', err);
+                uber.width.set.call(this, width);
+            }
         }
     });
 
@@ -1540,9 +1547,10 @@ function enableRetinaSupport() {
             return uber.height.get.call(this) / getPixelRatio(this);
         },
         set: function(height) {
-            var pixelRatio = getPixelRatio(this);
+            var pixelRatio = getPixelRatio(this),
+                context;
             uber.height.set.call(this, height * pixelRatio);
-            var context = this.getContext('2d');
+            context = this.getContext('2d');
             context.restore();
             context.save();
             context.scale(pixelRatio, pixelRatio);

store.js

@@ -61,7 +61,7 @@ normalizeCanvas*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.store = '2016-November-22';
+modules.store = '2016-November-24';
 
 
 // XML_Serializer ///////////////////////////////////////////////////////
@@ -390,10 +390,12 @@ SnapSerializer.prototype.rawLoadProjectModel = function (xmlNode) {
     if (model.pentrails) {
         project.pentrails = new Image();
         project.pentrails.onload = function () {
-            normalizeCanvas(project.stage.trailsCanvas);
-            var context = project.stage.trailsCanvas.getContext('2d');
-            context.drawImage(project.pentrails, 0, 0);
-            project.stage.changed();
+            if (project.stage.trailsCanvas) { // work-around a bug in FF
+                normalizeCanvas(project.stage.trailsCanvas);
+                var context = project.stage.trailsCanvas.getContext('2d');
+                context.drawImage(project.pentrails, 0, 0);
+                project.stage.changed();
+            }
         };
         project.pentrails.src = model.pentrails.contents;
     }