Option for message in table body when generating empty table.

[rjazwiec]

Prework

• [x] Read and abide by gt's code of conduct and contributing guidelines.
• [x ] Search for duplicates among the existing issues (both open and closed).

Proposal

Now gt generates only header of the table from the empty dataframe. It would be nice to have an option to generate empty table in the way R studio shows empty dataframe - header with message in the body "No data available in table" (or preferably custom message).

I generate many automatic crosscheck dataframes that sometimes are empty. (like samples that have combinations of features that shouldn't be present in dataset - potential errors in measurements or data collection). I automate printing reports from these crosschecks. When generating pdf, table with only header looks like error in LaTex - it suggests that something is not rendered there properly. Message in the body "This query returned 0 results" would make it look much more not error-like.

Radek