[yt-dev] Issue #697: when halo merger tree fails because it runs out of viable halos to track, give an appropriate error message (yt_analysis/yt)

[Cameron Hummels]

New issue 697: when halo merger tree fails because it runs out of viable halos to track, give an appropriate error message
https://bitbucket.org/yt_analysis/yt/issue/697/when-halo-merger-tree-fails-because-it

Cameron Hummels:

right now, when the halo merger tree runs out of halos as it tracks back in time (usually in the z>20 regime), it gives a generic error: 

========== Cycle 00006 (z=29.999961) ==========
Traceback (most recent call last):
  File "enzo.py", line 33, in <module>
    mt.save_halo_evolution('halos.h5')
  File "/home/uni05/mlatif/ytnew/yt-x86_64/src/yt-hg/yt/analysis_modules/halo_merger_tree/enzofof_merger_tree.py", line 507, in save_halo_evolution
    halo_id = self.levels[cycle_fin][0].halo_id
IndexError: list index out of range

It would be nice to have this give an error saying what actually happened--it ran out of halos!