fix: avoid recursive error handling

src/core/util/error.ts

@@ -4,6 +4,8 @@ import { inBrowser } from './env'
 import { isPromise } from 'shared/util'
 import { pushTarget, popTarget } from '../observer/dep'
 
+let isHandlingError = false
+
 export function handleError(err: Error, vm: any, info: string) {
   // Deactivate deps tracking while processing error handler to avoid possible infinite rendering.
   // See: https://github.com/vuejs/vuex/issues/1505
@@ -55,14 +57,21 @@ export function invokeWithErrorHandling(
 
 function globalHandleError(err, vm, info) {
   if (config.errorHandler) {
+    if (isHandlingError) {
+      logError(err, vm, info)
+      return
+    }
     try {
+      isHandlingError = true
       return config.errorHandler.call(null, err, vm, info)
     } catch (e: any) {
       // if the user intentionally throws the original error in the handler,
       // do not log it twice
       if (e !== err) {
         logError(e, null, 'config.errorHandler')
       }
+    } finally {
+      isHandlingError = false
     }
   }
   logError(err, vm, info)

test/unit/features/error-handling.spec.ts

@@ -216,6 +216,34 @@ describe('Error handling', () => {
     Vue.config.errorHandler = undefined
   })
 
+  it('should avoid recursive error handling when errorHandler triggers another error', () => {
+    const originalHandler = Vue.config.errorHandler
+    let handlerCalls = 0
+    Vue.config.errorHandler = (err, instance) => {
+      handlerCalls++
+      if (handlerCalls === 1 && instance) {
+        instance.$emit('boom')
+      }
+    }
+    new Vue({
+      created() {
+        this.$on('boom', () => {
+          throw new Error('error in boom')
+        })
+      },
+      render(h) {
+        throw new Error('error in render')
+      },
+      renderError(h, err) {
+        return h('div', err.toString())
+      }
+    }).$mount()
+    expect(handlerCalls).toBe(1)
+    expect('Error in event handler for "boom"').toHaveBeenWarned()
+    expect('Error: error in boom').toHaveBeenWarned()
+    Vue.config.errorHandler = originalHandler
+  })
+
   // event handlers that can throw errors or return rejected promise
   ;[
     ['single handler', '<div v-on:click="bork"></div>'],