diff --git a/web/src/blueslip_stacktrace.ts b/web/src/blueslip_stacktrace.ts
index 6c8706abb6..57caa07196 100644
--- a/web/src/blueslip_stacktrace.ts
+++ b/web/src/blueslip_stacktrace.ts
@@ -90,7 +90,7 @@ async function get_context(location: StackFrame): Promise<NumberedLine[] | undef
     if (fileName === undefined || lineNumber === undefined) {
         return undefined;
     }
-    let sourceContent: string;
+    let sourceContent: string | undefined;
     try {
         sourceContent = await sourceCache[fileName];
     } catch {