Clean up runtime errors, fix VueUIs opening offscreen (#14025)

* Clean up runtime errors, fix VueUIs opening offscreen

* woops

* myazaki is based

code/modules/projectiles/gun.dm

@@ -137,11 +137,12 @@
 	if(isnull(scoped_accuracy))
 		scoped_accuracy = accuracy
 
-	if (!pin && needspin)
-		pin = /obj/item/device/firing_pin
-
-	if(pin && needspin)
+	if (needspin)
+		if(!pin)
+			pin = /obj/item/device/firing_pin
 		pin = new pin(src)
+	else
+		pin = null
 
 	if(istype(loc, /obj/item/robot_module))
 		has_safety = FALSE