[GearSwap] fix enable/disable command output error message

disable() and enable() are called with a couple of values which returned from string:gsub() that are replaced string and found index.
So second argument is almost always 0, they never find the slot named "0".
remove unnecessary assignment
Merge pull request #1115 from kotodamagic/gearswap-fix-disenable

[GearSwap] enable/disable command always output error message