pos getBlockByNumber unmarshal error

[wanliqun]

Test with the following codes snippets with go sdk v1.0.19:

block, err := cfx.Pos().GetBlockByNumber(pos.NewBlockNumber(1))
 logrus.WithFields(logrus.Fields{
 "block": block, "error": err,
}).Info("Test post getBlockByNumber")

output:

INFO[0000] Test post getBlockByNumber block="" error="json: cannot unmarshal non-string into Go struct field Block.pivotDecision of type hexutil.Uint64"

[wanliqun]

error with cfx.Pos().GetBlockByNumber also