Annotate Error_Handler with noreturn to help analysis

[Avamander]

Summary

This PR annotates _Error_Handler with __attribute__((noreturn)) that informs the compiler that the given function does not return.

Motivation

This simplifies analysis for both the compiler and external tools.

For example it fixes a warning I got, that the result of getAssociatedChannel in HardwareTimer.cpp might* underflow when 1 is subtracted from the default return value of zero and this would then result in an out of bounds array access. "Might" in this context probably means to the compiler that there's either no Error_Handler defined or there's one that returns. In any case, the fact that these errors can pop up (like they did for me), means the code flow is not always clear enough for the compiler.

Additional notes

HardwareTimer and other similar files could maybe be updated in a way to fail/return safe values in all cases? Though this might cause undesirable seemingly working "default" behaviour while a crash would be very visible.

An another question is if there should there be a default halt loop Error_Handler even if NDEBUG is enabled (and a replacement is not defined). I lack sufficient experience with the core to know if this would be safer everything considered.

[fpistm]

Thanks for the PR, it makes sense.

HardwareTimer and other similar files could maybe be updated in a way to fail/return safe values in all cases? Though this might cause undesirable seemingly working "default" behaviour while a crash would be very visible.
If the value is not correct it fails in the error handler (infinite loop). Returning a safe value is not easy as we do not know which timer is used nor if something is connected to it.

An another question is if there should there be a default halt loop Error_Handler even if NDEBUG is enabled (and a replacement is not defined). I lack sufficient experience with the core to know if this would be safer everything considered.

If NDEBUG and not redefined, a default halt loop is defined (infiinite loop). So don't see what else we can do.