Regression test

Closes phpstan/phpstan#4926

tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -348,4 +348,9 @@ public function testRuleWithNullsafeVariant(): void
 		]);
 	}
 
+	public function testBug4926(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-4926.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Arrays/data/bug-4926.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Bug4926;
+
+/**
+ * @phpstan-type Data array{customer?: array{first_name: string}}
+ */
+class Foo
+{
+	/** @var Data */
+	private array $data = [];
+
+	public function getFirstName(): ?string
+	{
+		return $this->data['customer']['first_name'] ?? null;
+	}
+}