fixes

code/datums/elements/embed.dm

@@ -168,7 +168,7 @@
   * If we hit a valid target (carbon or closed turf), we create the shrapnel_type object and immediately call tryEmbed() on it, targeting what we impacted. That will lead
   *	it to call tryForceEmbed() on its own embed element (it's out of our hands here, our projectile is done), where it will run through all the checks it needs to.
   */
-/datum/element/embed/proc/checkEmbedProjectile(obj/projectile/P, atom/movable/firer, atom/hit, angle, hit_zone)
+/datum/element/embed/proc/checkEmbedProjectile(obj/item/projectile/P, atom/movable/firer, atom/hit, angle, hit_zone)
 	if(!iscarbon(hit) && !isclosedturf(hit))
 		Detach(P)
 		return // we don't care

code/game/objects/items/grenades/plastic.dm

@@ -207,7 +207,7 @@
 	else
 		return ..()
 
-/obj/item/grenade/c4/prime(mob/living/lanced_by)
+/obj/item/grenade/plastic/c4/prime(mob/living/lanced_by)
 	if(QDELETED(src))
 		return
 	. = ..()