fix case of Carrier drone crash

happen when commander or armcarry spawn 2 drone in succession and 2nd one is killed in same frame as its created.

happen because harmless bug in UpdateCoroutine() cause "SitOnPad()" loop to skip 1 frame and missed a NIL check.

and fix a harmless bug, where if 1st drone is destroyed, the gadget wait for next reloadtime to spawn 2nd drone.

+ some cleanup to PlayerLIst widget (revert adding a redundant checks)