test: remove unneeded assert()

Author: kenjis

tests/system/CommonSingleServiceTest.php

@@ -36,7 +36,6 @@ public function testSingleServiceWithNoParamsSupplied(string $service): void
         $service1 = single_service($service);
         $service2 = single_service($service);
 
-        assert($service1 !== null);
         assert($service1 !== null);
 
         $this->assertInstanceOf(get_class($service1), $service2);
@@ -67,7 +66,6 @@ public function testSingleServiceWithAtLeastOneParamSupplied(string $service): v
         $service1 = single_service($service, ...$params);
         $service2 = single_service($service, ...$params);
 
-        assert($service1 !== null);
         assert($service1 !== null);
 
         $this->assertInstanceOf(get_class($service1), $service2);