Remove unused $hasNonExistentMethod variable in findTypeAndMethodNames()

Make the by-reference parameter optional with a default value so
findTypeAndMethodNames() doesn't need to instantiate a variable it
never reads.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Type/Constant/ConstantArrayType.php

@@ -545,12 +545,11 @@ public function getCallableParametersAcceptors(ClassMemberAccessAnswerer $scope)
 	/** @return ConstantArrayTypeAndMethod[] */
 	public function findTypeAndMethodNames(): array
 	{
-		$hasNonExistentMethod = false;
-		return $this->doFindTypeAndMethodNames($hasNonExistentMethod);
+		return $this->doFindTypeAndMethodNames();
 	}
 
 	/** @return ConstantArrayTypeAndMethod[] */
-	private function doFindTypeAndMethodNames(bool &$hasNonExistentMethod): array
+	private function doFindTypeAndMethodNames(bool &$hasNonExistentMethod = false): array
 	{
 		if (count($this->keyTypes) !== 2) {
 			return [];