* abort() if the `expression' is false (ie. compares equal to zero)
* on debug builds (SILC_DEBUG defined), and prints error message to
* stderr on release builds (SILC_DEBUG undefined) but does not abort().
* abort() if the `expression' is false (ie. compares equal to zero)
* on debug builds (SILC_DEBUG defined), and prints error message to
* stderr on release builds (SILC_DEBUG undefined) but does not abort().