The exit_reason file can sometimes be misleading

[David Dickinson]

I find that the exit_reason file often tells me that the run finished as it used all of its timesteps when this isn’t necessarily true. For example when a run finishes due to using the available time I get

-1 GS2 internal time limit exceeded.
1 nstep timesteps completed.

in the exit_reason file. It would be good to make this more reliable/precise. This may be helped by improving the structure of the gs2_main and the main top level path through the code.