/errors: Empty args are not missing arguments

e.g. the hydration diff will always produce `/errors/418?args[]=` in prod because prod doesn't have diffs.

Author: eps1lon

src/components/MDX/ErrorDecoder.tsx

@@ -11,7 +11,7 @@ function replaceArgs(
   return msg.replace(/%s/g, function () {
     const arg = argList[argIdx++];
     // arg can be an empty string: ?args[0]=&args[1]=count
-    return arg === undefined || arg === '' ? replacer : arg;
+    return arg === undefined ? replacer : arg;
   });
 }