$ operator is invalid for atomic vectors

[dsamhat]

I have several Shiny apps running using Shiny Server.  Every few weeks I receive this error "$ operator is invalid for atomic vectors".  I found the fix to be just inserting a blank line in my server.R code and the saving the code.  I am not changing anything in the code.  Any ideas why I keep encountering this issue?

[Yihui Xie]

Is that the complete error message? Normally R will tell you where the
error came from, e.g.

Error in session$sendInputMessage : $ operator is invalid for atomic vectors

Without the name of the function that signaled the error, it will be
difficult to diagnose the problem.

Regards,
Yihui

[dsamhat]

Hi Yihui, 

Yes that is the complete error message that displays on the Shiny app page where my Google charts would be.  It is hard to replicate locally in R and it seems to only happen on R Server.  In any case, it continues to happen and the fix is adding an empty line to my code and saving it.  Any further thoughts?

Thanks, 
David

[ZJ]

I get this error if I passed the session to the function wrong. e.g. suppose the function f has two arguments like so f(session, something_else) then if i didn't pass session to it or I accidentally used something else as the first argument then I get something like this.

[Yihui Xie]

ZJ: that is also my first reaction :)

David: sorry, I have no other ideas...

Regards,
Yihui