Error with NA variable

[VLDrenth]

When using data where a variable is NA for all observations, this variable can still be selected. When the robmed or OLS is then run, the GUI stops with console warning: Warning: Error in fit_mediation.default: not enough observations.

[aalfons]

The GUI should catch errors and warnings when executing test_mediation() and then give a more helpful message in the main panel that lists a few common issues and suggestions (e.g., check for missing values or other issues of the data, try increasing the number of bootstrap samples, etc.).