Fix hasSession specifier

src/Type/Symfony/RequestTypeSpecifyingExtension.php

@@ -46,10 +46,15 @@ public function specifyTypes(MethodReflection $methodReflection, MethodCall $nod
 	{
 		$classReflection = $this->broker->getClass(self::REQUEST_CLASS);
 		$methodVariants = $classReflection->getNativeMethod(self::GET_METHOD_NAME)->getVariants();
+		$returnType = ParametersAcceptorSelector::selectSingle($methodVariants)->getReturnType();
+
+		if (!TypeCombinator::containsNull($returnType)) {
+			return new SpecifiedTypes();
+		}
 
 		return $this->typeSpecifier->create(
 			new MethodCall($node->var, self::GET_METHOD_NAME),
-			TypeCombinator::removeNull(ParametersAcceptorSelector::selectSingle($methodVariants)->getReturnType()),
+			TypeCombinator::removeNull($returnType),
 			$context
 		);
 	}

tests/Type/Symfony/ImpossibleCheckTypeMethodCallRuleTest.php

@@ -0,0 +1,32 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Symfony;
+
+use PHPStan\Rules\Comparison\ImpossibleCheckTypeMethodCallRule;
+use PHPStan\Rules\Rule;
+
+/**
+ * @extends \PHPStan\Testing\RuleTestCase<ImpossibleCheckTypeMethodCallRule>
+ */
+class ImpossibleCheckTypeMethodCallRuleTest extends \PHPStan\Testing\RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return self::getContainer()->getByType(ImpossibleCheckTypeMethodCallRule::class);
+	}
+
+	public function testExtension(): void
+	{
+		$this->analyse([__DIR__ . '/data/request_get_session.php'], []);
+	}
+
+	public static function getAdditionalConfigFiles(): array
+	{
+		return [
+			__DIR__ . '/../../../extension.neon',
+			__DIR__ . '/../../../vendor/phpstan/phpstan-strict-rules/rules.neon',
+		];
+	}
+
+}