fix debug.traceback() return nil in lua5.1 (#818)

pilaoda · web-flow · commit 170317055de9 · 2020-03-09T20:46:48.000+01:00
diff --git a/src/lualib/SourceMapTraceBack.ts b/src/lualib/SourceMapTraceBack.ts
@@ -7,7 +7,12 @@ function __TS__SourceMapTraceBack(this: void, fileName: string, sourceMap: { [li
     if (globalThis.__TS__originalTraceback === undefined) {
         globalThis.__TS__originalTraceback = debug.traceback;
         debug.traceback = (thread, message, level) => {
-            const trace = globalThis.__TS__originalTraceback(thread, message, level);
+            let trace: string;
+            if (thread === undefined && message === undefined && level === undefined) {
+                trace = globalThis.__TS__originalTraceback();
+            } else {
+                trace = globalThis.__TS__originalTraceback(thread, message, level);
+            }
 
             if (typeof trace !== "string") {
                 return trace;
