title: RStudio - no symbol named 'X' in scope
body: <p>Why do I get the yellow triangular warnings in the LHS margin in RStudio when using packages like dplyr?  When I begin to use my current version of RStudio (1.0.136) there are no warnings. Then I start to code, mistype something, and a whole bunch of the yellow triangles appear. Yet if I restart RStudio, I begin again with none.</p>
  
  <p><a href="https://i.stack.imgur.com/IinR5.png" rel="noreferrer"><img src="https://i.stack.imgur.com/IinR5.png" alt="no symbol named X in scope"></a> </p>
  
  <p>Is there a way to suppress and/or prevent this?</p>