References codelens shows 0 when guru fails

[ramya-rao-a]

The codelens for references uses the guru tool behind the scenes to provide references.
When guru fails, the codelens shows "0 references" instead of alluding to the fact that the tool has failed behind the scenes

The console shows failures from guru with details on the command being called with args as well as a call stack. The call stack is related to node and the child process that was spawned for guru and is pointless

cc @JeffreyRichter

[ramya-rao-a]

With 68a8d1f, the below changes are made:

• The codelens would say "Error finding references" instead of "0 references" if there was error in running the guru tool
• When there is error running the guru tool, the console will show the command and the args being passed as before. The call stack related to node and child process will not be shown

[ramya-rao-a]

The fix is out in the latest update to the Go extension (0.6.69)