More informative error messages for batch_calc_ES()

[jepusto]

It'd be nice to have more informative error messages for batch_calc_ES() that would make it possible to identify specific issues with data series for which effect sizes can't be calculated. For example:

• Series with no treatment phases
• Series with only a single baseline observation or single treatment observation

Also try such examples with the specific effect size calculation functions including NAP() and Tau_BC() to see if the error messages can be improved there.

[jepusto]

Also make sure that these get passed in to the Shiny app.