queue: queue.Take() returns an invalid task

The patch fixes the return an invalid task object from queue.Take().
It may happen if an encoded task data has a nil value [1].

After the fix queue.Take() returns a nil value in the case.

1. https://github.com/msgpack/msgpack/blob/master/spec.md#nil-format

Author: oleg-jukovec

CHANGELOG.md

@@ -35,6 +35,7 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 - Decimal package use a test function GetNumberLength instead of a
   package-level function getNumberLength (#219)
 - Datetime location after encode + decode is unequal (#217)
+- queue.Take() returns an invalid task (#222)
 
 ## [1.8.0] - 2022-08-17
 

queue/queue.go

@@ -467,6 +467,14 @@ func (qd *queueData) DecodeMsgpack(d *decoder) error {
 	}
 
 	qd.task = &Task{data: qd.result, q: qd.q}
-	d.Decode(&qd.task)
+	if err = d.Decode(&qd.task); err != nil {
+		return err
+	}
+
+	if qd.task.Data() == nil {
+		// It may happen if the decoder has a code.Nil value inside. As a
+		// result, the task will not be decoded.
+		qd.task = nil
+	}
 	return nil
 }

queue/task.go

@@ -29,13 +29,9 @@ func (t *Task) DecodeMsgpack(d *decoder) error {
 		return err
 	}
 	if t.data != nil {
-		if err = d.Decode(t.data); err != nil {
-			return fmt.Errorf("fffuuuu: %s", err)
-		}
-	} else {
-		if t.data, err = d.DecodeInterface(); err != nil {
-			return err
-		}
+		d.Decode(t.data)
+	} else if t.data, err = d.DecodeInterface(); err != nil {
+		return err
 	}
 	return nil
 }