fix(compiler-core): v-on inline async function expression handler (#4569)

fix #4568

packages/compiler-core/src/transforms/vOn.ts

@@ -16,7 +16,8 @@ import { validateBrowserExpression } from '../validateExpression'
 import { hasScopeRef, isMemberExpression } from '../utils'
 import { TO_HANDLER_KEY } from '../runtimeHelpers'
 
-const fnExpRE = /^\s*([\w$_]+|\([^)]*?\))\s*=>|^\s*function(?:\s+[\w$]+)?\s*\(/
+const fnExpRE =
+  /^\s*([\w$_]+|(async\s*)?\([^)]*?\))\s*=>|^\s*(async\s+)?function(?:\s+[\w$]+)?\s*\(/
 
 export interface VOnDirectiveNode extends DirectiveNode {
   // v-on without arg is handled directly in ./transformElements.ts due to it affecting