I've made error messages along the lines of "If you see this then something has unexpectedly gone wrong <description of error the developer would understand>" f

I've made error messages along the lines of "If you see this then something has unexpectedly gone wrong <description of error the developer would understand>" for cases when the error condition should never occur under normal circumstances and should have been trapped for and solved earlier in the process, this being a belt-and-braces catch-all message as a last resort.