to_bytes/to_unicode: Don't use errors="strict"
to_bytes/to_unicode: Don't use errors="strict"

So that we can use these functions when formatting exceptions & error
messages, without causing a new Unicode exception that will obscure the
original.

stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester