test: refs #8647 revert saveFn string

src/components/CrudModel.vue

@@ -61,7 +61,7 @@ const $props = defineProps({
         default: null,
     },
     saveFn: {
-        type: [String, Function],
+        type: Function,
         default: null,
     },
     beforeSaveFn: {

src/components/__tests__/CrudModel.spec.js

@@ -21,7 +21,7 @@ describe('CrudModel', () => {
                 dataKey: 'crudModelKey',
                 model: 'crudModel',
                 url: 'crudModelUrl',
-                saveFn: '',
+                saveFn: vi.fn(),
             },
         });
         wrapper = wrapper.wrapper;
@@ -223,7 +223,7 @@ describe('CrudModel', () => {
             expect(vm.isLoading).toBe(false);
             expect(vm.hasChanges).toBe(false);
 
-            await wrapper.setProps({ saveFn: '' });
+            await wrapper.setProps({ saveFn: null });
         });
 
         it("should use default url if there's not saveFn", async () => {