Merge pull request #3109 from Citadel-Station-13/upstream-merge-31232

[MIRROR] Fixes mech fab runtime

code/datums/components/material_container.dm

@@ -17,6 +17,7 @@
 	var/show_on_examine
 	var/list/allowed_typecache
 	var/last_inserted_type
+	var/last_inserted_id
 	var/last_amount_inserted
 	var/last_insert_success
 	var/datum/callback/precondition
@@ -116,7 +117,7 @@
 	if(!amt)
 		return 0
 
-	insert_materials(S,amt)
+	last_inserted_id = insert_materials(S,amt)
 	last_inserted_type = S.type
 	S.use(amt)
 	last_amount_inserted = amt
@@ -133,17 +134,22 @@
 	if(!material_amount || !has_space(material_amount))
 		return 0
 
-	insert_materials(I, multiplier)
+	last_inserted_id = insert_materials(I, multiplier)
 	last_inserted_type = I.type
 	last_amount_inserted = material_amount
 	return material_amount
 
 /datum/component/material_container/proc/insert_materials(obj/item/I, multiplier = 1) //for internal usage only
 	var/datum/material/M
+	var/primary_mat
+	var/max_mat_value = 0
 	for(var/MAT in materials)
 		M = materials[MAT]
 		M.amount += I.materials[MAT] * multiplier
 		total_amount += I.materials[MAT] * multiplier
+		if(I.materials[MAT] > max_mat_value)
+			primary_mat = MAT
+	return primary_mat
 
 //For consuming material
 //mats is a list of types of material to use and the corresponding amounts, example: list(MAT_METAL=100, MAT_GLASS=200)