Add test for phpstan/phpstan#10938: check if Iterator is empty via never

Adds nsrt and rule test coverage for the related issue where checking
if a collection is empty using (TValue is never ? true : bool)
conditional return type was not working.

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

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/bug-10938.php

@@ -0,0 +1,28 @@
+<?php declare(strict_types = 1);
+
+namespace Bug10938;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template TKey
+ * @template TValue
+ * @extends \IteratorAggregate<TKey, TValue>
+ */
+interface Collection extends \IteratorAggregate
+{
+	/**
+	 * @return (TValue is never ? true : bool)
+	 */
+	function isEmpty(): bool;
+}
+
+/** @param Collection<never, never> $c */
+function emptyCollection(Collection $c): void {
+	assertType('true', $c->isEmpty());
+}
+
+/** @param Collection<int, string> $c */
+function nonEmptyCollection(Collection $c): void {
+	assertType('bool', $c->isEmpty());
+}