Handle unsaved tab deletion correctly

Author: facchinm

app/src/processing/app/SketchController.java

@@ -253,13 +253,21 @@ public void handleDeleteCode() throws IOException {
         sketch.delete();
         editor.base.handleClose(editor);
       } else {
+
+        boolean neverSavedTab = !current.fileExists();
+
         // delete the file
-        if (!current.delete(sketch.getBuildPath().toPath())) {
+        if (!current.delete(sketch.getBuildPath().toPath()) && !neverSavedTab) {
           Base.showMessage(tr("Couldn't do it"),
                            I18n.format(tr("Could not delete \"{0}\"."), current.getFileName()));
           return;
         }
 
+        if (neverSavedTab) {
+          // remove the file from the sketch list
+          sketch.removeFile(current);
+        }
+
         editor.removeTab(current);
 
         // just set current tab to the main tab