fix: update deprecations

Author: g105b

src/LogConfig.php

@@ -49,7 +49,10 @@ public static function setDefaultHandlerLevel(string $level):void {
 		self::$defaultHandlerLevel = $level;
 	}
 
-	public static function addHandler(LogHandler $handler, string $logLevel = null):void {
+	public static function addHandler(
+		LogHandler $handler,
+		?string $logLevel = null,
+	):void {
 		array_push(self::$handlers, $handler);
 		array_push(self::$handlerLevels, $logLevel ?? self::$defaultHandlerLevel);
 	}

test/phpunit/LogTest.php

@@ -72,7 +72,7 @@ public function test_levelOutput_all():void {
 
 		Log::debug("This is not critical!");
 		Log::critical("This is critical!");
-		$output = self::getActualOutput();
+		$output = self::getActualOutputForAssertion();
 		self::assertStringContainsString("This is critical!", $output);
 		self::assertStringContainsString("This is not critical!", $output);
 	}