added error handling to file saving (don't know how to cause errors, so haven't been able to test properly)

lib/tiles/offlineEnabler.js

@@ -188,10 +188,26 @@ define([
 						if(evt=="end")
 						{
 							var blob = new Blob([ csv.join("\r\n") ], {type:"text/plain;charset=utf-8"});
-							FileSaver.saveAs(blob, fileName);
+							var saver = FileSaver.saveAs(blob, fileName);
-							// fails in Safari (and iPad Safari?)
+							
+							if( saver.readyState == saver.DONE )
+							{
+								if( saver.error )
+									return callback(false,"Error saving file " + fileName);
+								else
+									return callback(true, "Saved " + (csv.length-1) + " tiles (" + Math.floor(blob.size / 1024 / 1024 * 100) / 100 + " Mb) into " + fileName);								
+							}
+							else
+							{
+								saver.onerror = function(evt) {
+									callback(false,"Error saving file " + fileName);
+								}
+								saver.onwriteend = function(evt)
+								{
 									callback(true, "Saved " + (csv.length-1) + " tiles (" + Math.floor(blob.size / 1024 / 1024 * 100) / 100 + " Mb) into " + fileName);								
 								}
+							}
+						}
 						else
 						{
 							csv.push(url+","+img);
@@ -212,6 +228,10 @@ define([
 							var csvContent = evt.target.result;
 							var tiles = csvContent.split("\r\n");
 							var tileCount = 0;
+
+							if(tiles[0] != "url,img")
+								return callback(false, "File " + file.name + " doesn't contain tiles that can be loaded");
+
 							for(var i=1; i<tiles.length; i++)
 							{
 								var pair = tiles[i].split(',');