Why does luaV_execute use runtime_check instead of luaG_runerror in OP_SETLIST?

["Peter Cawley" <lua@...>]

For OP_FORPREP, luaG_runerror is called if any of the values aren't
numbers, and luaG_runerror is used elsewhere in the VM to indicate a
runtime error to the caller. However, OP_SETLIST calls runtime_check
if the value isn't a table, and then silently skips to the next
instruction without an error. Why is this the only place where
runtime_check is used, and why is it used instead of luaG_runerror?