Add regression test for #13694

Author: takaram

tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php

@@ -1169,4 +1169,14 @@ public function testBug8719(): void
 		$this->analyse([__DIR__ . '/data/bug-8719.php'], []);
 	}
 
+	public function testBug13694(): void
+	{
+		$this->cliArgumentsVariablesRegistered = true;
+		$this->polluteScopeWithLoopInitialAssignments = true;
+		$this->checkMaybeUndefinedVariables = true;
+		$this->polluteScopeWithAlwaysIterableForeach = true;
+
+		$this->analyse([__DIR__ . '/data/bug-13694.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/bug-13694.php

@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * @param int[] $keys
+ * @param array<int, int|null> $things
+ */
+function evaluateThings(array $keys, array $things): void
+{
+	foreach ($keys as $key) {
+		if (array_key_exists($key, $things) && $things[$key] === null) {
+			echo "Value for key $key is null\n";
+			continue;
+		}
+
+		if (isset($things[$key])) {
+			echo "Key $key is set\n";
+		}
+	}
+}