"Error: argument is of length zero" when optimized search parameters box is checked

[benjaminplace]

In console, we get a warning:

Warning: Error in if: argument is of length zero
  97: renderUI [C:\Users\bjp\Documents\code_repository\R\dimspec\inst\apps\msmatch/server.R#754]
  96: func
  83: renderFunc
  82: output$search_compounds_match_top
   1: shiny::runApp

This is due to the optimized search parameters returning an MS2 with no mz/intensity values. Suggested fix is to make a check that, when it fails (no mz/int values), it gives a descriptive pop-up message that includes the potential remedy (uncheck optimized search parameters).