CLDSRV-546: debugged prepareStream

Author: Will Toozs

lib/api/apiUtils/object/prepareStream.js

@@ -13,7 +13,7 @@ const V4Transform = require('../../../auth/streamingV4/V4Transform');
  * the type of request requires them
  */
 function prepareStream(stream, streamingV4Params, log, errCb) {
-    if (stream.headers['x-amz-content-sha256'] ===
+    if (stream && stream.headers && stream.headers['x-amz-content-sha256'] ===
         'STREAMING-AWS4-HMAC-SHA256-PAYLOAD') {
         if (typeof streamingV4Params !== 'object') {
             // this might happen if the user provided a valid V2