🔧 fix: #1346 cannot declare 'mep' twice

Author: SaltyAom

.github/ISSUE_TEMPLATE/2-bug-report.yml

@@ -29,6 +29,7 @@ body:
       attributes:
         label: What environment are you using
         description: |
+              Answer with runtime and version you are using.
               - Bun version: `bun --version`
               - Node version: `node --version`
               - Deno version: `deno --version`

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 1.3.11 - 18 Aug 2025
+Bug fix:
+- [#1346](https://github.com/elysiajs/elysia/issues/1346) cannot declare 'mep' twice 
+
 # 1.3.10 - 18 Aug 2025
 Bug fix:
 - [#1028](https://github.com/elysiajs/elysia/issues/1028) query array nuqs format in dynamic mode

package.json

@@ -1,7 +1,7 @@
 {
 	"name": "elysia",
 	"description": "Ergonomic Framework for Human",
-	"version": "1.3.10",
+	"version": "1.3.11",
 	"author": {
 		"name": "saltyAom",
 		"url": "https://github.com/SaltyAom",

src/compose.ts

@@ -1969,6 +1969,8 @@ export const composeHandler = ({
 		else fnLiteral += `c.code=error.code??error[ERROR_CODE]??"UNKNOWN"\n`
 
 		fnLiteral += `let er\n`
+		// Mapped error Response
+		if (hooks.mapResponse?.length) fnLiteral += 'let mep\n'
 
 		for (let i = 0; i < hooks.error.length; i++) {
 			const endUnit = errorReporter.resolveChild(hooks.error[i].fn.name)
@@ -1987,9 +1989,6 @@ export const composeHandler = ({
 					total: hooks.mapResponse?.length
 				})
 
-				// Mapped error Response
-				fnLiteral += 'let mep\n'
-
 				for (let i = 0; i < hooks.mapResponse.length; i++) {
 					const mapResponse = hooks.mapResponse[i]