expose empty body as empty string

Author: sanderhahn

src/utils/serve-functions.js

@@ -177,12 +177,14 @@ function createHandler(dir) {
     var isBase64Encoded = false;
     var body = request.body;
 
-    if (body instanceof Buffer) {
+    if (body === undefined || Object.keys(body).length === 0) {
+      // handle empty body (https://github.com/expressjs/body-parser/issues/288)
+      body = "";
+    } else if (body instanceof Buffer) {
       isBase64Encoded = true;
       body = body.toString("base64");
-    } else if(body.toString) {
-      isBase64Encoded = false;
-      body = body.toString();
+    } else if(typeof(body) === "string") {
+      // body is already processed as string
     }
 
     const lambdaRequest = {