Meson is a far more robust build framework, compared to autotools. This
greatly simplifies adding new features, since it's far easier to
maintain a set of meson.build files vs the autotools mishmash.
DEPRECATION NOTICE: Autotools based build is deprecated and will be
removed in the future.
Since the introduction of X macros to the CLI handling code, there will
never be a condition where the handler will be NULL. This is a legacy
check from when the code had individual maps that were maintained by
hand.
Prior to this change, on failure condition, x52cli would exit with a
code that mapped directly to the return code of the function. This was
inconsistent with the behaviour if the initialization or connect steps
failed for any reason.