Not sure I love the idea of stdlib panicking on purpose here. I haven't looked at the code, but I wonder if it's just in functions that don't currently return an error for backwards compat...
This kind of behavior is useful when things are only detectable at runtime. Rudimentary test coverage would uproot it.
Warning log levels should be avoided; it's either important and actionable (error or fatal), or it isn't, in which case it's 'info' log level. I had a blog post about it (appeal to authority) but I can't find it at the moment.
Also consider it a way to avoid hidden bugs, similar to "The server chose violence" [1] [2] as well as how much Postel's law held back interoperability (which is forgotten by many aspect of FIPS certifications)