fix(sig): update workaround

lib/sig.js

@@ -134,12 +134,12 @@ const extractDecipherWithName = (exports.d2 = body => {
   }
 });
 
-const getExtractFunctions = (extractFunctions, body) => {
+const getExtractFunctions = (extractFunctions, body, postProcess = null) => {
   for (const extractFunction of extractFunctions) {
     try {
       const func = extractFunction(body);
       if (!func) continue;
-      return new vm.Script(func);
+      return new vm.Script(postProcess ? postProcess(func) : func);
     } catch (err) {
       continue;
     }
@@ -193,7 +193,9 @@ const extractNTransformWithName = (exports.n2 = body => {
 let nTransformWarning = false;
 const extractNTransform = body => {
   // Faster: extractNTransformFunc
-  const nTransformFunc = getExtractFunctions([extractNTransformFunc, extractNTransformWithName], body);
+  const nTransformFunc = getExtractFunctions([extractNTransformFunc, extractNTransformWithName], body, code =>
+    code.replace(/if\(typeof \S*==="undefined"\)return \S*;/, ""),
+  );
   if (!nTransformFunc && !nTransformWarning) {
     // This is optional, so we can continue if it's not found, but it will bottleneck the download.
     console.warn(