BaseInput.js: Avoid a dangling dataInput value

Upon removal an auto submit is unconditionally fired.
i.e. even without any removed terms, it is. The submit
didn't ran in this case, but the data input was populated
anyway.

asset/js/widget/BaseInput.js

@@ -574,12 +574,12 @@ define(["../notjQuery", "Completer"], function ($, Completer) {
                 }
             }
 
-            this.dataInput.value = JSON.stringify({
-                type: changeType,
-                terms: changedTerms
-            });
-
             if (Object.keys(changedTerms).length) {
+                this.dataInput.value = JSON.stringify({
+                    type: changeType,
+                    terms: changedTerms
+                });
+
                 $(this.input.form).trigger('submit', { submittedBy: input });
             }
         }