fix(client): check weapon specialAmmo is a string

If I had a nickel for every person that reported a reloading bug due
to indexing a number value on line 444, I'd have two nickels; which
isn't a lot, but it's weird that it happened twice.

client.lua

@@ -439,7 +439,7 @@ local function useSlot(slot)
  useItem(data, function(resp)
  if not resp or resp.name ~= currentWeapon?.ammo then return end
 
- if currentWeapon.metadata.specialAmmo ~= resp.metadata.type then
+ if currentWeapon.metadata.specialAmmo ~= resp.metadata.type and type(currentWeapon.metadata.specialAmmo) == 'string' then
  local clipComponentKey = ('%s_CLIP'):format(Items[currentWeapon.name].model:gsub('WEAPON_', 'COMPONENT_'))
  local specialClip = ('%s_%s'):format(clipComponentKey, (resp.metadata.type or currentWeapon.metadata.specialAmmo):upper())