Fix panic in find_words due to string access outside of a character boundary

[MakotoE]

Closes #390

This fixes an attempt to access string bytes that may be within a character boundary.

Please check if this is actually how the code should be. All I know is that all tests pass.

[mgeisler]

Thanks! I'll double-check this when I'm home and then merge. We should really address #280 since I hope it could have cought this.

[MakotoE]

We should really address #280 since I hope it could have cought this.

I wouldn't run fuzz tests for all CI runs because you want commit tests to be fast. I think it should be run every night (on days when commits are merged). Or perhaps having a bot run it when requested in a PR might be good. There is a trade-off between being able to run fuzz tests for a long period of time occasionally or a short period of time frequently.

[mgeisler]

Thanks for the PR, I'll make a 0.14.1 release with the fix now.

I wouldn't run fuzz tests for all CI runs because you want commit tests to be fast.

Yeah, I wouldn't want to prolong the tests by half or full hours. in this case, it turns out that the bug can be found by fuzzing for less than a minute. So I'll setup very brief fuzz testing on PRs, just to have a quick sanity check in the future.