Certain cctkGH members (eg nghostzones) do not contain useful values in all modes, eg not in LEVEL mode. This causes problems every once in a while, eg: #2288.

Using the CHECKED macros we can actually avoid defining C / Fortran variables for those members when a scheduled functions is scheduled only in a given mode and turn a runtime error into a compile time error.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2418/have-declare_cctk_arguments_checked-hide