New issue 559: The TotalMass derived quantity fails when no particles are present https://bitbucket.org/yt_analysis/yt/issue/559/the-totalmass-derived-quantit... Nathan Goldbaum: As brought up by Mark Krumholz on the mailing list: http://paste.yt-project.org/show/3445/ We should check to make sure particles are in the dataset before including them instead of assuming they're there. Responsible: ngoldbaum