allow assigned_member deletion

src/store/modules/feature.store.js

@@ -277,7 +277,8 @@ const feature = {
             status: state.form.status.value.value || state.form.status.value,
             project: rootState.projects.project.slug,
             feature_type: rootState['feature-type'].current_feature_type_slug,
-            assigned_member: state.form.assigned_member.value,
+            // if is undefined using null to allow sending empty field in order to delete previous assigned_member
+            assigned_member: state.form.assigned_member.value ? state.form.assigned_member.value : null,
             ...extraFormObject
           }
         };