So sure you don't want to log everything in Prod, but maybe you do in Dev. In that case, a bug would be to push the dev logging configuration to Prod. Oops.

If you have the clear text password at any point in your codebase, then there is no full-proof way to prevent to log it unintentionally as the result of a bug. You just have to be extra-careful ( code review, minimal amount code manipulating it, prod-like testing environment with log scanner, ...)