title_body: Blockchain Simulator Chokes on Validation Error
upvoted_answer: The problem is that in the off-chain wallet code, after submitting the transaction, there is a line of code that waits for the transaction to be confirmed. Seeing as the transaction is invalid, it will never be confirmed, so the wallet contract blocks on that line forever.
  There would be workarounds, but in the final version of Plutus, it will be possible to check the status of validation from the wallet and for example detect if the transaction was invalid.
  This means handling this and similar situations will be much easier in future.