fix: Check typeof result instead of constructor of function

Author: astuyve

packages/dd-trace/src/lambda/handler.js

@@ -86,10 +86,13 @@ exports.datadog = function datadog (lambdaHandler) {
     const context = extractContext(args)
 
     checkTimeout(context)
-    if (lambdaHandler.constructor.name === 'AsyncFunction') {
-      return Promise.resolve(lambdaHandler.apply(this, args))
-        .then((res) => { clearTimeout(__lambdaTimeout); return res })
+    const result = lambdaHandler.apply(this, args)
+    if (result && typeof result.then === 'function') {
+      return result.then((res) => {
+        clearTimeout(__lambdaTimeout)
+        return res
+      })
     }
-    return lambdaHandler.apply(this, args)
+    return result
   }
 }