fix: prefer registered error code

src/compose.ts

@@ -2058,8 +2058,8 @@ export const composeHandler = ({
 				'c.code="VALIDATION"\n' +
 				'c.set.status=422' +
 				'}else{' +
-				`c.code=error.code??error[ERROR_CODE]??"UNKNOWN"}`
-		else fnLiteral += `c.code=error.code??error[ERROR_CODE]??"UNKNOWN"\n`
+				`c.code=error[ERROR_CODE]??error.code??"UNKNOWN"}`
+		else fnLiteral += `c.code=error[ERROR_CODE]??error.code??"UNKNOWN"\n`
 
 		fnLiteral += `let er\n`
 		// Mapped error Response
@@ -2657,7 +2657,7 @@ export const composeErrorHandler = (app: AnyElysia) => {
 	fnLiteral +=
 		`const set=context.set\n` +
 		`let _r\n` +
-		`if(!context.code)context.code=error.code??error[ERROR_CODE]\n` +
+		`if(!context.code)context.code=error[ERROR_CODE]??error.code\n` +
 		`if(!(context.error instanceof Error))context.error=error\n` +
 		`if(error instanceof ElysiaCustomStatusResponse){` +
 		`set.status=error.status=error.code\n` +

src/dynamic-handle.ts

@@ -3,6 +3,7 @@ import type { Context } from './context'
 import { parseCookie } from './cookies'
 import {
 	ElysiaCustomStatusResponse,
+	ERROR_CODE,
 	type ElysiaErrors,
 	NotFoundError,
 	status,
@@ -880,7 +881,14 @@ export const createDynamicErrorHandler = (app: AnyElysia) => {
 		},
 		error: ElysiaErrors
 	) => {
-		const errorContext = Object.assign(context, { error, code: error.code })
+		const registeredCode = (error as Error & { [ERROR_CODE]?: string })[
+			ERROR_CODE
+		]
+
+		const errorContext = Object.assign(context, {
+			error,
+			code: registeredCode ?? error.code
+		})
 		errorContext.set = context.set
 
 		if (

test/lifecycle/error.test.ts

@@ -124,6 +124,34 @@ describe('error', () => {
 		expect(response.status).toBe(500)
 	})
 
+	it.each([true, false])(
+		'uses registered error key over instance code with aot: %p',
+		async (aot) => {
+			class InvalidUrlError extends Error {
+				code = 'invalid_url' as const
+
+				constructor() {
+					super('internal message')
+				}
+			}
+
+			const app = new Elysia({ aot })
+				.error({ INVALID_URL: InvalidUrlError })
+				.onError(({ code }) => {
+					if (code === 'INVALID_URL')
+						return new Response('handled', { status: 422 })
+				})
+				.get('/', () => {
+					throw new InvalidUrlError()
+				})
+
+			const response = await app.handle(req('/'))
+
+			expect(response.status).toBe(422)
+			expect(await response.text()).toBe('handled')
+		}
+	)
+
 	it.each([true, false])(
 		'return correct number status on error function with aot: %p',
 		async (aot) => {