Mech fixes

- Fixes mech mining scanner being unclickable
- Fixes mech action buttons breaking upon being regranted

code/game/mecha/equipment/tools/mining_tools.dm

@@ -112,6 +112,7 @@
 	var/scanning = 0
 
 /obj/item/mecha_parts/mecha_equipment/mining_scanner/New()
+	..()
 	START_PROCESSING(SSobj, src)
 
 /obj/item/mecha_parts/mecha_equipment/mining_scanner/attach(obj/mecha/M)

code/game/mecha/mecha_actions.dm

@@ -25,7 +25,8 @@
 	var/obj/mecha/chassis
 
 /datum/action/innate/mecha/Grant(mob/living/L, obj/mecha/M)
-	chassis = M
+	if(M)
+		chassis = M
 	..()
 
 /datum/action/innate/mecha/Destroy()