1 files changed, 3 insertions, 1 deletions
diff --git a/cli/tests/unit/opcall_test.ts b/cli/tests/unit/opcall_test.ts
index 7e3685320..e38f481d9 100644
--- a/cli/tests/unit/opcall_test.ts
+++ b/cli/tests/unit/opcall_test.ts
@@ -12,7 +12,9 @@ unitTest(async function sendAsyncStackTrace() {
     await Deno.read(rid, buf);
     unreachable();
   } catch (error) {
-    const s = error.stack.toString();
+    assert(error instanceof Error);
+    const s = error.stack?.toString();
+    assert(s);
     console.log(s);
     assertStringIncludes(s, "opcall_test.ts");
     assertStringIncludes(s, "read");