Add assertion on invalid cache set (microsoft#43845)

Author: weswigham

src/compiler/checker.ts

@@ -32190,6 +32190,9 @@ namespace ts {
                     assignBindingElementTypes(declaration.name, links.type);
                 }
             }
+            else if (type) {
+                Debug.assertEqual(links.type, type, "Parameter symbol already has a cached type which differs from newly assigned type");
+            }
         }
 
         // When contextual typing assigns a type to a parameter that contains a binding pattern, we also need to push