Fix coverage (#2332).

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@22822 b5f69653-2bf5-0310-8201-b0dafb8e1405
Fix segfault on program exit caused by r22733.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@22823 b5f69653-2bf5-0310-8201-b0dafb8e1405