Hi Haris,
when I use the Show Label as Tool Tip command on a non-existing label (say, on \eqref{ZZZ} when no \label{ZZZ} exists), instead of the expected Not Found message I get inserted into the file undefined method `context' for nil:NilClass so I guess you might add a check on the nillness of context in your script.
If you find the time to work on it, maybe you might also consider this small request (I see that some infrastructure is already in place in LaTeXUtils): a similar command to work on citations, i.e. when invoked on a \cite, the tooltip shows the corresponding bibitem, possibly finding it into the .bbl file. I guess the two things (for labels and citations) could happily coexist in the same script.
Thank you for your work, Piero