data_color() to include column name in error message

[sanjmeh]

data_color() is great, however a little error message improvement is desired.

Existing error

Error in scales::col_numeric: Wasn't able to determine range of domain
  118: stop
  117: scales::col_numeric
  116: data_color
   97: render_gt [/home/.../server.R#2631]
   96: func
   83: renderFunc
   82: output$pilfer_gt_tab
    1: runApp

Proposal

The column name should also be provided (column that failed in the scales::col_numeric call). It would avoid manually testing each column. This is especially painful when we use data_color() from server.R for a large number of columns.

[rich-iannone]

I can try to make this better by getting ahead of a potential scales error. Could you provide some example code where this error might occur?