13.4.1 beta release (MC 1.21.4)

• Fixed crash when applying invalid camouflage to a router (specifically a Camouflage Upgrade which was clicked on an Extruder Mk2 template frame block)
  • Existing invalid Camouflage Upgrades installed in routers will now do nothing (no camo, no crash!)
  • Trying to click a block which is invalid for camo (modular router or template frame) with a Camouflage Upgrade now displays a client error message
  • Added a modularouters:camo_blacklist block tag (empty by default) to which other blocks can be added if desired