[IoTDB 0.11]Error occurs when selecting Last from an empty timeseries with no cached value

[wshao08]

This bug only occurs in IoTDB 0.11.
When querying Last value from an empty timeseries, the server gives an exception and no result output.

To Reproduce:

1. Create a new timeseries

CREATE TIMESERIES root.sg.d1.temperature WITH DATATYPE=FLOAT, ENCODING=RLE

2. Query last value of this timeseries

select last temperature from root.sg.d1

This bug is fixed in PR: #2226