why wasn't this already the case? o_o

this should fix the char server freeze bug

When an NPC called destroy; from an attached script, npc_id, and
associated state, was not properly cleared. This meant that the
server considered the PC to still be in conversation, preventing
many actions including walking, but with an invalid NPC.

This clears state for the specific case of the a PC attached to
the script instance that called destroy. It is still not safe to
call destroy; if other players may be attached to it.

There's no reason for it to be deprecated in the first place