current_dc is a macro that determines the dive computer
based on the current dive number. When the planner is started
from an emtpy dive list, the dive number ends up being -1 and
that doesn't produce a valid dive computer. Use the divecomputer
of the displayed_dive instead. This is done via a macro that
can also be used in two other places. Without this patch, the
planner crashed when called on an empty dive list.
Signed-off-by: Robert C. Helling <helling@atdotde.de>
a422957cd6