fix error message when attempting to view data frame with no cols
fix error message when attempting to view data frame with no cols

jar1karp/rstudio,JanMarvin/rstudio,jar1karp/rstudio,jar1karp/rstudio,JanMarvin/rstudio,jar1karp/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,jrnold/rstudio,JanMarvin/rstudio,jrnold/rstudio,jrnold/rstudio,JanMarvin/rstudio,jrnold/rstudio,jar1karp/rstudio,jrnold/rstudio,jrnold/rstudio,JanMarvin/rstudio,jrnold/rstudio,jrnold/rstudio,JanMarvin/rstudio,jar1karp/rstudio,jrnold/rstudio,jar1karp/rstudio,jar1karp/rstudio,jar1karp/rstudio,JanMarvin/rstudio