From 3b365dd8ba13d15e7041e65f1f9f713ae4867b2e Mon Sep 17 00:00:00 2001
From: Frederik Wessberg <frederikwessberg@gmail.com>
Date: Sat, 30 Jul 2022 00:31:54 +0200
Subject: [PATCH] chore: add null-check

---
 .../evaluate-property-access-expression.ts    |  2 +-
 test/assignments/assignments.test.ts          | 27 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/interpreter/evaluator/evaluate-property-access-expression.ts b/src/interpreter/evaluator/evaluate-property-access-expression.ts
index b90a0b1..29ce122 100644
--- a/src/interpreter/evaluator/evaluate-property-access-expression.ts
+++ b/src/interpreter/evaluator/evaluate-property-access-expression.ts
@@ -11,7 +11,7 @@ export function evaluatePropertyAccessExpression(options: EvaluatorOptions<TS.Pr
 	const {evaluate, node, statementTraversalStack, environment, typescript, getCurrentError} = options;
 	const expressionResult = evaluate.expression(node.expression, options) as IndexLiteral;
 
-	if (getCurrentError() != null) {
+	if (expressionResult == null || getCurrentError() != null) {
 		return;
 	}
 
diff --git a/test/assignments/assignments.test.ts b/test/assignments/assignments.test.ts
index 906b4ca..da0b610 100644
--- a/test/assignments/assignments.test.ts
+++ b/test/assignments/assignments.test.ts
@@ -21,3 +21,30 @@ test("Can evaluate a CallExpression for a function with variable assignments. #1
 	if (!result.success) t.fail(result.reason.stack);
 	else t.deepEqual(result.value, 4);
 });
+
+test("Can evaluate a CallExpression for a function with variable assignments. #2", withTypeScript, (t, {typescript, useTypeChecker}) => {
+	const {result} = executeProgram(
+		`
+		const mapOfMaps: Map<string, Map<string, string>> = new Map();
+
+		function getMapForKey(key: string): string {
+
+			let innerMap = mapOfMaps.get(key);
+			if (innerMap == null) {
+				innerMap = new Map();
+				mapOfMaps.set(key, innerMap);
+			}
+
+			return innerMap;
+		}
+
+		mapOfMaps.set("foo", new Map());
+		getMapForKey("foo");
+		`,
+		"getMapForKey(",
+		{typescript, useTypeChecker}
+	);
+
+	if (!result.success) t.fail(result.reason.stack);
+	else t.deepEqual(result.value, new Map());
+});