regex parse error on garrysmod

[naturallymitchell]

regex parse error:
    =\s*require\s*"RegisterConstraint( _name_ , _function_, "
                                     ^
error: unclosed group
stack traceback:
	[C]: in field 'match'
	init.lua:234: in upvalue 'parse_assignments'
	init.lua:225: in upvalue 'parse_assignments'
	init.lua:225: in local 'parse_assignments'
	init.lua:256: in local 'init_f'
	[string "?"]:5: in function <[string "?"]:1>
	[C]: in function 'xpcall'
	[string "?"]:1: in main chunk