fix #5: do not panic if previous error handler returns null

composer.json

@@ -49,7 +49,11 @@
         ]
     },
     "config": {
-        "sort-packages": true
+        "sort-packages": true,
+        "allow-plugins": {
+            "dealerdirect/phpcodesniffer-composer-installer": true,
+            "phpstan/extension-installer": true
+        }
     },
     "extra": {
         "branch-alias": {

lib/Util/ErrorHandler.php

@@ -32,7 +32,7 @@ public static function handleError(int $errorNumber, string $errorString): bool
     {
         // Do not raise an exception when the error suppression operator (@) was used.
         if (! ($errorNumber & error_reporting())) {
-            return call_user_func_array(self::$previous, func_get_args());
+            return call_user_func_array(self::$previous, func_get_args()) ?? false;
         }
 
         switch ($errorNumber) {
@@ -49,7 +49,7 @@ public static function handleError(int $errorNumber, string $errorString): bool
                 throw new Error($errorString, $errorNumber);
         }
 
-        return call_user_func_array(self::$previous, func_get_args());
+        return call_user_func_array(self::$previous, func_get_args()) ?? false;
     }
 
     public static function register(): void

phpunit.xml.dist

@@ -12,6 +12,7 @@
   <testsuites>
     <testsuite name="Project Test Suite">
       <directory>tests/</directory>
+      <directory suffix=".phpt">tests/</directory>
     </testsuite>
   </testsuites>
 </phpunit>

tests/Util/ErrorHandlerTest.php

@@ -75,4 +75,17 @@ public function testShouldPassErrorsToPreviousErrorHandlerIfSilenced(): void
         self::assertNotNull($error);
         self::assertEquals('unlink(this_file_does_not_exist.bad_idea): No such file or directory', $error[1]);
     }
+
+    public function testShouldNotCrashIfPreviousErrorHandlerReturnsNullOrVoid(): void
+    {
+        $this->expectNotToPerformAssertions();
+
+        ErrorHandler::unregister();
+        $previous = set_error_handler(static function () use (&$previous): void {
+            call_user_func_array($previous, func_get_args());
+        });
+
+        ErrorHandler::register();
+        @unlink('this_file_does_not_exist.bad_idea');
+    }
 }

tests/Util/error-handler-user-error.phpt

@@ -0,0 +1,15 @@
+--TEST--
+ErrorHandler - Test User Error does throw Error
+--FILE--
+<?php
+
+use Kcs\ClassFinder\Util\ErrorHandler;
+
+require __DIR__ . '/../../vendor/autoload.php';
+
+ErrorHandler::register();
+trigger_error('This is an error', E_USER_ERROR);
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Kcs\ClassFinder\Util\Error: This is an error in %a

tests/Util/error-handler-user-notice.phpt

@@ -0,0 +1,15 @@
+--TEST--
+ErrorHandler - Test User Notice does not throw Error
+--FILE--
+<?php
+
+use Kcs\ClassFinder\Util\ErrorHandler;
+
+require __DIR__ . '/../../vendor/autoload.php';
+
+ErrorHandler::register();
+trigger_error('This is a notice', E_USER_NOTICE);
+
+?>
+--EXPECTF--
+Notice: This is a notice in %a

tests/Util/error-handler-user-warning.phpt

@@ -0,0 +1,15 @@
+--TEST--
+ErrorHandler - Test User Warning does not throw Error
+--FILE--
+<?php
+
+use Kcs\ClassFinder\Util\ErrorHandler;
+
+require __DIR__ . '/../../vendor/autoload.php';
+
+ErrorHandler::register();
+trigger_error('This is a warning', E_USER_WARNING);
+
+?>
+--EXPECTF--
+Warning: This is a warning in %a

tests/Util/error-handler-void-previous-handler.phpt

@@ -0,0 +1,17 @@
+--TEST--
+ErrorHandler - Test User Notice does not panic if previous handler returns void
+--FILE--
+<?php
+
+use Kcs\ClassFinder\Util\ErrorHandler;
+
+require __DIR__ . '/../../vendor/autoload.php';
+
+set_error_handler(static function (): void {});
+
+ErrorHandler::register();
+trigger_error('This is a notice', E_USER_NOTICE);
+
+?>
+--EXPECTF--
+Notice: This is a notice in %a