Use error handler instead of error suppression

Fixes #200.

Author: trowski

src/Context/Internal/process-runner.php

@@ -13,7 +13,12 @@
 
 // Doesn't exist in phpdbg...
 if (\function_exists("cli_set_process_title")) {
-    @\cli_set_process_title("amp-process");
+    \set_error_handler(static fn () => true);
+    try {
+        \cli_set_process_title("amp-process");
+    } finally {
+        \restore_error_handler();
+    }
 }
 
 (function (): void {

src/Context/ProcessContext.php

@@ -106,11 +106,7 @@ public static function start(
                     self::$pharCopy = \sys_get_temp_dir() . "/phar-" . \bin2hex(\random_bytes(10)) . ".phar";
                     \copy(\Phar::running(false), self::$pharCopy);
 
-                    \register_shutdown_function(static function (): void {
-                        if (self::$pharCopy !== null) {
-                            @\unlink(self::$pharCopy);
-                        }
-                    });
+                    \register_shutdown_function(static fn () => self::unlinkExternalCopy(self::$pharCopy));
 
                     $path = "phar://" . self::$pharCopy . "/" . \substr($path, \strlen(\Phar::running(true)));
                 }
@@ -121,11 +117,7 @@ public static function start(
                 self::$pharScriptPath = $scriptPath = \sys_get_temp_dir() . "/amp-process-runner-" . $suffix . ".php";
                 \file_put_contents($scriptPath, $contents);
 
-                \register_shutdown_function(static function (): void {
-                    if (self::$pharScriptPath !== null) {
-                        @\unlink(self::$pharScriptPath);
-                    }
-                });
+                \register_shutdown_function(static fn () => self::unlinkExternalCopy(self::$pharScriptPath));
             }
 
             // Monkey-patch the script path in the same way, only supported if the command is given as array.
@@ -176,6 +168,20 @@ public static function start(
         return new self($process, $ipcChannel, $resultChannel);
     }
 
+    private static function unlinkExternalCopy(?string $filepath): void
+    {
+        if ($filepath === null) {
+            return;
+        }
+
+        \set_error_handler(static fn () => true);
+        try {
+            \unlink($filepath);
+        } finally {
+            \restore_error_handler();
+        }
+    }
+
     /**
      * @return non-empty-list<string>
      */