fix: missed first stream frame

Signed-off-by: Valery Piashchynski <piashchynski.valery@gmail.com>

pool/static_pool/workers_pool.go

@@ -230,6 +230,9 @@ begin:
  sp.ww.Release(w)
  }()
 
+ // send the initial frame
+ resp <- newPExec(rsp, nil)
+
  // stream iterator
  for {
  select {
@@ -241,14 +244,15 @@ begin:
  }
  runtime.Goexit()
  default:
- pld, next, err := w.StreamIter()
- if err != nil {
- resp <- newPExec(nil, err) // exit from the goroutine
+ pld, next, errI := w.StreamIter()
+ if errI != nil {
+ resp <- newPExec(nil, errI) // exit from the goroutine
  runtime.Goexit()
  }
 
  resp <- newPExec(pld, nil)
  if !next {
+ // we've got the last frame
  runtime.Goexit()
  }
  }