The perl svn::client module has a tendency to produce some quite obscure error messages, such as this beauty that cropped up recently, generated when calling the status callback function.

perl: subversion/libsvn_subr/path.c:114: svn_path_join: Assertion `svn_path_is_canonical(base, pool)

A bit of digging with Data::Dumper revealed that this was caused by a path that was inadvertently postfixed with two sequential forward slashes - which the native C client doesn’t seem to mind at all..