diff --git a/src/lualib/SourceMapTraceBack.ts b/src/lualib/SourceMapTraceBack.ts
index 374f52b10..edad12c45 100644
--- a/src/lualib/SourceMapTraceBack.ts
+++ b/src/lualib/SourceMapTraceBack.ts
@@ -8,6 +8,11 @@ function __TS__SourceMapTraceBack(this: void, fileName: string, sourceMap: { [li
         globalThis.__TS__originalTraceback = debug.traceback;
         debug.traceback = (thread, message, level) => {
             const trace = globalThis.__TS__originalTraceback(thread, message, level);
+
+            if (typeof trace !== "string") {
+                return trace;
+            }
+
             const [result] = string.gsub(trace, "(%S+).lua:(%d+)", (file, line) => {
                 const fileSourceMap = globalThis.__TS__sourcemap[file + ".lua"];
                 if (fileSourceMap && fileSourceMap[line]) {