TaskIds on the STDIN cause error

[noirello]

There is a problem with the script. The task IDs - which could be sent back after emitting - on standard input are not handled and cause the following error:
Error in t$tuple : $ operator is invalid for atomic vectors

Found out, that the Task ID is represented as a JSON list in a Storm message something like this:
[7] end

This list will be converted to a vector in the process_json method with fromJSON function, then try to access to the tuple field (line 109 in Strom.R), which is invalid for a vector.

This error will break the R processes in a few seconds after bolt has been initialized.