This may not be the fastest way to go about it, but that's the only way I can think of:
Try re-downloading the game. Extract it in a different folder. Make a backup of your current game. Try replacing all of the .js files in the '/www/js' folder and then restart the game. If that fixes your problem, restore the .js files from the backup, and try replacing them one by one, until you find the one that causes this. If that does not fix your problem, try doing the same with other folders.
Edit: I just thought you do not actually need to replace them one by one. You can replace half of the files (say, the top half, alphabetically), and if that works, half of those files, to narrow it down faster.