The function enableVirtualTerminalProcessing must return an error if
virtual terminal processing (only applicable on Windows) was not
enabled, otherwise we assume that the terminal supports both 256-color
and truecolor.
We have been erroneously assuming that all non-Windows terminals are
256-color and sending escape sequences to those that cannot intepret
them. This led to some parts of Survey prompts being invisible on old
terminals.
Regressed in be4b392530
efe504eefc