From 3b3e1fc38a8e2763679fc11ff07aed1617946867 Mon Sep 17 00:00:00 2001
From: Douglas Christopher Wilson <doug@somethingdoug.com>
Date: Sat, 20 Jun 2015 15:20:35 -0400
Subject: [PATCH] Fix hiding platform issues with decodeURIComponent

closes #2652
---
 History.md          |  2 ++
 lib/router/layer.js | 13 ++++++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/History.md b/History.md
index 5778a23bba..b591d9d0d8 100644
--- a/History.md
+++ b/History.md
@@ -3,6 +3,8 @@ unreleased
 
   * Fix `res.format` error when only `default` provided
   * Fix issue where `next('route')` in `app.param` would incorrectly skip values
+  * Fix hiding platform issues with `decodeURIComponent`
+    - Only `URIError`s are a 400
   * Fix using `*` before params in routes
   * Fix using capture groups before params in routes
   * Simplify `res.cookie` to call `res.append`
diff --git a/lib/router/layer.js b/lib/router/layer.js
index b5c1f58958..a29cf26bfc 100644
--- a/lib/router/layer.js
+++ b/lib/router/layer.js
@@ -152,19 +152,22 @@ Layer.prototype.match = function match(path) {
  *
  * @param {string} val
  * @return {string}
- * @api private
+ * @private
  */
 
-function decode_param(val){
+function decode_param(val) {
   if (typeof val !== 'string') {
     return val;
   }
 
   try {
     return decodeURIComponent(val);
-  } catch (e) {
-    var err = new TypeError("Failed to decode param '" + val + "'");
-    err.status = 400;
+  } catch (err) {
+    if (err instanceof URIError) {
+      err.message = 'Failed to decode param \'' + val + '\'';
+      err.status = 400;
+    }
+
     throw err;
   }
 }