public static void showBlockingError(String title, String msg) {
		Swing.runNow(() -> Msg.showError(MergeManager.class, null, title, msg));
	}
Display a blocking error popup.  When used from a {@link MergeResolver} task it will 
prevent that task from exiting/progressing until the error popup is dismissed.
@param title popup title
@param msg error message
Ghidra/Features/Base/src/main/java/ghidra/app/merge/MergeManager.java