bowtie smoke should check that a harness doesn't fully crash even when sent invalid input

[Julian]

Obviously Bowtie attempts not to send invalid test cases to harnesses.

However, even when sending valid input, implementations can have bugs, and those bugs can occasionally cause crashes.

Because of this, we encourage harnesses to catch any language-level exceptions and return error responses rather than letting the process crash, which can mean needing to restart the Docker container (something likely much more "expensive").

It would be nice if bowtie smoke gave harness authors feedback on whether the harness is properly resilient against crashes, and sending invalid input is likely to be one reliable way to test this.