helpful error on unhashable parameters

[zzstoatzz]

closes #16042

in cases where a user attempts to pass an unhashable object to a task and we fail to compute a cache key, we should at least raise a helpful error.

I could be convinced that we should somehow attempt to change the items we hash for the key automatically, but I didn't want to start with magic

[codspeed-hq]

CodSpeed Performance Report

Merging #16049 will not alter performance

_{Comparing better-hashing-error (6ffdeff) with main (c2a3fb5)}

Summary

✅ 3 untouched benchmarks

[desertaxle]

Nice!