Merge pull request #1564 from adobe/randy/issue-1544

Fix bugs #1543 and #1544: working set files are not guaranteed to be openable, so check for failure; defer assertion until it's (supposed to be) guaranteed to be valid

src/document/DocumentManager.js

@@ -409,15 +409,22 @@ define(function (require, exports, module) {
 
             // Switch editor to next document (or blank it out)
             if (nextFile) {
-                CommandManager.execute(Commands.FILE_OPEN, { fullPath: nextFile.fullPath });
+                CommandManager.execute(Commands.FILE_OPEN, { fullPath: nextFile.fullPath })
+                    .done(function () {
+                        // (Now we're guaranteed that the current document is not the one we're closing)
+                        console.assert(!(_currentDocument && _currentDocument.file.fullPath === file.fullPath));
+                    })
+                    .fail(function () {
+                        // File chosen to be switched to could not be opened, and the original file
+                        // is still in editor. Close it again so code will try to open the next file,
+                        // or empty the editor if there are no other files. 
+                        closeFullEditor(file);
+                    });
             } else {
                 _clearCurrentDocument();
             }
         }
 
-        // (Now we're guaranteed that the current document is not the one we're closing)
-        console.assert(!(_currentDocument && _currentDocument.file.fullPath === file.fullPath));
-
         // Remove closed doc from working set, if it was in there
         // This happens regardless of whether the document being closed was the current one or not
         removeFromWorkingSet(file);