Having no TotalBuildTimes along a positive CircuitBuildAbandonedCount
count lead to a segfault. We check for that condition and then BUG + log
warn if that is the case.
It should never happened in theory but if someone modified their state
file, it can lead to this problem so instead of segfaulting, warn.
Fixes#40437
Signed-off-by: David Goulet <dgoulet@torproject.org>