fix: should not swallow user catch on rejected promise in methods

fix #9694

src/core/util/error.js

@@ -43,10 +43,11 @@ export function invokeWithErrorHandling (
   let res
   try {
     res = args ? handler.apply(context, args) : handler.call(context)
-    if (res && !res._isVue && isPromise(res)) {
+    if (res && !res._isVue && isPromise(res) && !res._handled) {
+      res.catch(e => handleError(e, vm, info + ` (Promise/async)`))
       // issue #9511
-      // reassign to res to avoid catch triggering multiple times when nested calls
-      res = res.catch(e => handleError(e, vm, info + ` (Promise/async)`))
+      // avoid catch triggering multiple times when nested calls
+      res._handled = true
     }
   } catch (e) {
     handleError(e, vm, info)

test/unit/modules/util/invoke-with-error-handling.spec.js → test/unit/modules/util/error.spec.js

@@ -6,14 +6,17 @@ describe('invokeWithErrorHandling', () => {
     it('should errorHandler call once when nested calls return rejected promise', done => {
       const originalHandler = Vue.config.errorHandler
       const handler = Vue.config.errorHandler = jasmine.createSpy()
+      const userCatch = jasmine.createSpy()
+      const err = new Error('fake error')
 
       invokeWithErrorHandling(() => {
         return invokeWithErrorHandling(() => {
-          return Promise.reject(new Error('fake error'))
+          return Promise.reject(err)
         })
-      }).then(() => {
+      }).catch(userCatch).then(() => {
         Vue.config.errorHandler = originalHandler
         expect(handler.calls.count()).toBe(1)
+        expect(userCatch).toHaveBeenCalledWith(err)
         done()
       })
     })