Fix missing condition

Author: danielwe

src/compiler.jl

@@ -6563,11 +6563,11 @@ end
         prev = getfield(x, i)
         next = getfield(y, i)
         ST = Core.Typeof(prev)
-        if !mutable_register(ST)
-            recursive_add(prev, next, f, forcelhs)
-        elseif !(ST <: Integer)
+        if mutable_register(ST) && !(ST <: Integer)
             recursive_accumulate(prev, next, f)
             prev
+        else
+            recursive_add(prev, next, f, forcelhs)
         end
     end)
 end