InvalidArgumentException: Attribute name must be a string in file /var/task/vendor/nyholm/psr7/src/ServerRequest.php

[DanRVP]

When parsing path parameters like /{param} an exception is thrown. Stack trace:

InvalidArgumentException: Attribute name must be a string in file /var/task/vendor/nyholm/psr7/src/ServerRequest.php on line 174
Stack trace:
  1. InvalidArgumentException->() /var/task/vendor/nyholm/psr7/src/ServerRequest.php:174
  2. Nyholm\Psr7\ServerRequest->withAttribute() /var/task/vendor/bref/dev-server/src/Router.php:119
  3. Bref\DevServer\Router->addPathParameters() /var/task/vendor/bref/dev-server/src/Router.php:76
  4. Bref\DevServer\Router->match() /var/task/vendor/bref/dev-server/src/Handler.php:45
  5. Bref\DevServer\Handler->handleRequest() /var/task/vendor/bref/dev-server/src/server-handler.php:11

This is caused by preg_match returning numeric keys in Router::addPathParameters() line 119:

Input from preg_match() looks like:

array(2) {
  [0]=>
  string(11) "param_value"
  ["param"]=>
  string(11) "param_value"
}

I ran this setup in Docker with the image bref/php-83-dev:3. I have not submitted a PR as I am not sure if passing these numeric keys is a feature which needs to be maintained or a bug which needs to be patched.