fix: use MemLocation.copy for zeroRest

src/main/wacc/backend/asmGenerator.scala

@@ -381,7 +381,7 @@ object asmGenerator {
       stack.size == stackSizeStart + 1,
       "Sanity check: ONLY the evaluated expression should have been pushed onto the stack"
     )
-    asm ++= zeroRest(MemLocation(base = stack.head.base, opSize = Some(Q64)), expr.ty.size)
+    asm ++= zeroRest(stack.head.copy(opSize = Some(Q64)), expr.ty.size)
     asm
   }