fix: add tests from review

Author: ga-devfront

tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php

@@ -1181,6 +1181,10 @@ public function testBug13353(): void
 				'Variable $bar might not be defined.',
 				11,
 			],
+			[
+				'Undefined variable: $bar',
+				20
+			]
 		]);
 	}
 

tests/PHPStan/Rules/Variables/data/bug-13353.php

@@ -9,3 +9,13 @@
 }
 
 echo $$foo;
+
+function () {
+	$foo = 'bar';
+
+	if (!isset($$foo)) {
+		echo 'Wololo';
+	}
+
+	echo $$foo;
+};