NaNs at very high order on small elements in 3D

The script code/results.py as recorded in papers/2017-qbx-fmm-3d@526a532ef311446664d47b20b3bc752ed85a8121 with pytential 7a48859a produces NaNs for the smallest bits of the geometry:

(The yellow bits are the NaNs.)

That case is using an order-30 FMM and order-9 QBX. Aside from the NaNs it gives 8 digits.

cc @mattwala