minor #51096 Use more "First class callable syntax" + Normalize set_error_handler/set_exception_handler calls (lyrixx)

This PR was merged into the 6.4 branch.

Discussion
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Use more "First class callable syntax" + Normalize set_error_handler/set_exception_handler calls

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |

Commits
-------

be1bbbccc1 Use more "First class callable syntax" + Normalize set_error_handler/set_exception_handler calls

Author: nicolas-grekas

Server/Connection.php

@@ -62,7 +62,7 @@ public function write(Data $data): bool
         $context = array_filter($context);
         $encodedPayload = base64_encode(serialize([$data, $context]))."\n";
 
-        set_error_handler(fn () => true);
+        set_error_handler(static fn () => null);
         try {
             if (-1 !== stream_socket_sendto($this->socket, $encodedPayload)) {
                 return true;
@@ -87,7 +87,7 @@ public function write(Data $data): bool
      */
     private function createSocket()
     {
-        set_error_handler(fn () => true);
+        set_error_handler(static fn () => null);
         try {
             return stream_socket_client($this->host, $errno, $errstr, 3) ?: null;
         } finally {