Running test_adapt.py results in core dumping

[dohertyw1]

Hi there,

When I try and run test_adapt.py the test fails and leaves me with the following error:

target mesh has 224 nodes
Colinearity detection ...
Beginning PRAgMaTIc adapt
Initialising PRAgMaTIc ...
python: /home/will/pragmatic/include/Mesh.h:2619: void Mesh<real_t>::compute_ref_length() [with real_t = double]: Assertion `std::isnormal(Lref)' failed.
Aborted (core dumped)

The other tests run fine. I am running Ubuntu 20.04 and Fenics 2018. Could anyone help? Thanks.