Doctests not catching exceptions from show

This type of doctest, where show throws an error, does not work currently:

julia> gd
Error showing value of type GroupedDataFrame{DataFrame}:
ERROR: AssertionError: The current number of rows in the parent data frame is 3 and it does not match the number of rows it contained when GroupedDataFrame was created which was 2. The number of rows in the parent data frame has likely been changed unintentionally (e.g. using subset!, filter!, delete!, push!, or append! functions).

I believe it's because Documenter does not handle exceptions from the show calls which happen here: https://github.com/JuliaDocs/Documenter.jl/blob/6c8679bac445ab1c656744075b13a57835081cc3/src/DocTests.jl#L319

X-ref https://github.com/JuliaData/DataFrames.jl/pull/2811