Fix NPE in /timings command. Fixes #1323

/timings would NPE with a null BAKED_HANDLERS, as it is first initialized
in the CustomTimingsHandler constructor. Regressed in recent Spigot-API
update, though it does not occur in vanilla Spigot, since MCPC+ is not yet
fully updated with all the latest Spigot changes.

Added empty array initialization, to fix this NPE for now, although may
require further investigation or MCPC+ updates to latest Spigot patches
for a more complete fix.