Offset2D of ellipse causes segmentation fault

Offset2D on ellipse crashes. Both in cq-editor and when executed using plain python.

## To Reproduce

```python
import cadquery as cq
result = cq.Workplane().ellipse(0.5, 0.5)
result = result.offset2D(0.2)
```

## Backtrace

No backtrace, SIGSEGV

## Environment

OS: Fedora 34

Was CadQuery installed using Conda?:
Output of `conda list` from your active Conda environment:
```
# packages in environment at /home/msivak/Developer/miniconda/envs/cadquery:
#
# Name Version Build Channel
_libgcc_mutex 0.1 conda_forge conda-forge
_openmp_mutex 4.5 1_gnu conda-forge
alabaster 0.7.12 py_0 conda-forge
alsa-lib 1.2.3 h516909a_0 conda-forge
argh 0.26.2 pyh9f0ad1d_1002 conda-forge
astroid 2.8.0 py39hf3d152e_0 conda-forge
async_generator 1.10 py_0 conda-forge
atomicwrites 1.4.0 pyh9f0ad1d_0 conda-forge
attrs 21.2.0 pyhd8ed1ab_0 conda-forge
autopep8 1.5.6 pyhd8ed1ab_0 conda-forge
babel 2.9.1 pyh44b312d_0 conda-forge
backcall 0.2.0 pyh9f0ad1d_0 conda-forge
backports 1.0 py_2 conda-forge
backports.functools_lru_cache 1.6.4 pyhd8ed1ab_0 conda-forge
black 21.9b0 pyhd8ed1ab_0 conda-forge
bleach 4.1.0 pyhd8ed1ab_0 conda-forge
brotlipy 0.7.0 py39h3811e60_1001 conda-forge
bzip2 1.0.8 h7f98852_4 conda-forge
c-ares 1.17.2 h7f98852_0 conda-forge
ca-certificates 2021.5.30 ha878542_0 conda-forge
cadquery master py3.9 cadquery
certifi 2021.5.30 py39hf3d152e_0 conda-forge
cffi 1.14.6 py39h4bc2ebd_1 conda-forge
chardet 4.0.0 py39hf3d152e_1 conda-forge
click 8.0.1 py39hf3d152e_0 conda-forge
cloudpickle 2.0.0 pyhd8ed1ab_0 conda-forge
colorama 0.4.4 pyh9f0ad1d_0 conda-forge
cq-editor master py3.9 cadquery
cryptography 3.4.7 py39hbca0aa6_0 conda-forge
curl 7.79.1 h2574ce0_1 conda-forge
dataclasses 0.8 pyhc8e2a94_3 conda-forge
dbus 1.13.6 h48d8840_2 conda-forge
debugpy 1.4.1 py39he80948d_0 conda-forge
decorator 5.1.0 pyhd8ed1ab_0 conda-forge
defusedxml 0.7.1 pyhd8ed1ab_0 conda-forge
diff-match-patch 20200713 pyh9f0ad1d_0 conda-forge
docutils 0.17.1 py39hf3d152e_0 conda-forge
double-conversion 3.1.5 h9c3ff4c_2 conda-forge
eigen 3.4.0 h4bd325d_0 conda-forge
entrypoints 0.3 pyhd8ed1ab_1003 conda-forge
expat 2.4.1 h9c3ff4c_0 conda-forge
ezdxf 0.17 py39h1a9c180_0 conda-forge
ffmpeg 4.3.2 hca11adc_0 conda-forge
flake8 3.8.4 py_0 conda-forge
font-ttf-dejavu-sans-mono 2.37 hab24e00_0 conda-forge
font-ttf-inconsolata 3.000 h77eed37_0 conda-forge
font-ttf-source-code-pro 2.038 h77eed37_0 conda-forge
font-ttf-ubuntu 0.83 hab24e00_0 conda-forge
fontconfig 2.13.1 hba837de_1005 conda-forge
fonts-conda-ecosystem 1 0 conda-forge
fonts-conda-forge 1 0 conda-forge
freeimage 3.18.0 h88c329d_7 conda-forge
freetype 2.10.4 h0708190_1 conda-forge
future 0.18.2 py39hf3d152e_3 conda-forge
gettext 0.19.8.1 h73d1719_1008 conda-forge
gl2ps 1.4.2 h0708190_0 conda-forge
glew 2.1.0 h9c3ff4c_2 conda-forge
glib 2.68.4 h9c3ff4c_1 conda-forge
glib-tools 2.68.4 h9c3ff4c_1 conda-forge
gmp 6.2.1 h58526e2_0 conda-forge
gnutls 3.6.13 h85f3911_1 conda-forge
gst-plugins-base 1.18.5 hf529b03_0 conda-forge
gstreamer 1.18.5 h76c114f_0 conda-forge
hdf4 4.2.15 h10796ff_3 conda-forge
hdf5 1.10.6 nompi_h6a2412b_1114 conda-forge
icu 68.1 h58526e2_0 conda-forge
idna 2.10 pyh9f0ad1d_0 conda-forge
ilmbase 2.5.5 h780b84a_0 conda-forge
imagesize 1.2.0 py_0 conda-forge
importlib-metadata 4.8.1 py39hf3d152e_0 conda-forge
importlib_metadata 4.8.1 hd8ed1ab_0 conda-forge
intervaltree 3.0.2 py_0 conda-forge
ipykernel 6.4.1 py39hef51801_0 conda-forge
ipython 7.28.0 py39hef51801_0 conda-forge
ipython_genutils 0.2.0 py_1 conda-forge
isort 5.9.3 pyhd8ed1ab_0 conda-forge
jbig 2.1 h7f98852_2003 conda-forge
jedi 0.17.2 py39hf3d152e_1 conda-forge
jeepney 0.7.1 pyhd8ed1ab_0 conda-forge
jinja2 3.0.1 pyhd8ed1ab_0 conda-forge
jpeg 9d h36c2ea0_0 conda-forge
jsoncpp 1.9.4 h4bd325d_3 conda-forge
jsonschema 4.0.1 pyhd8ed1ab_0 conda-forge
jupyter_client 7.0.5 pyhd8ed1ab_0 conda-forge
jupyter_core 4.8.1 py39hf3d152e_0 conda-forge
jupyterlab_pygments 0.1.2 pyh9f0ad1d_0 conda-forge
jxrlib 1.1 h7f98852_2 conda-forge
keyring 23.2.1 py39hf3d152e_0 conda-forge
krb5 1.19.2 hcc1bbae_2 conda-forge
lame 3.100 h7f98852_1001 conda-forge
lazy-object-proxy 1.6.0 py39h3811e60_0 conda-forge
lcms2 2.12 hddcbb42_0 conda-forge
ld_impl_linux-64 2.36.1 hea4e1c9_2 conda-forge
lerc 2.2.1 h9c3ff4c_0 conda-forge
libblas 3.9.0 11_linux64_openblas conda-forge
libcblas 3.9.0 11_linux64_openblas conda-forge
libclang 11.1.0 default_ha53f305_1 conda-forge
libcurl 7.79.1 h2574ce0_1 conda-forge
libdeflate 1.7 h7f98852_5 conda-forge
libedit 3.1.20191231 he28a2e2_2 conda-forge
libev 4.33 h516909a_1 conda-forge
libevent 2.1.10 hcdb4288_3 conda-forge
libffi 3.4.2 h9c3ff4c_4 conda-forge
libgcc-ng 11.2.0 h1d223b6_9 conda-forge
libgfortran-ng 11.2.0 h69a702a_9 conda-forge
libgfortran5 11.2.0 h5c6108e_9 conda-forge
libglib 2.68.4 h174f98d_1 conda-forge
libglu 9.0.0 he1b5a44_1001 conda-forge
libgomp 11.2.0 h1d223b6_9 conda-forge
libiconv 1.16 h516909a_0 conda-forge
liblapack 3.9.0 11_linux64_openblas conda-forge
libllvm11 11.1.0 hf817b99_2 conda-forge
libnetcdf 4.8.0 nompi_hcd642e3_103 conda-forge
libnghttp2 1.43.0 h812cca2_1 conda-forge
libogg 1.3.4 h7f98852_1 conda-forge
libopenblas 0.3.17 pthreads_h8fe5266_1 conda-forge
libopus 1.3.1 h7f98852_1 conda-forge
libpng 1.6.37 h21135ba_2 conda-forge
libpq 13.3 hd57d9b9_0 conda-forge
libraw 0.20.2 h10796ff_1 conda-forge
libsodium 1.0.18 h36c2ea0_1 conda-forge
libspatialindex 1.9.3 h9c3ff4c_4 conda-forge
libssh2 1.10.0 ha56f1ee_2 conda-forge
libstdcxx-ng 11.2.0 he4da1e4_9 conda-forge
libtheora 1.1.1 h7f98852_1005 conda-forge
libtiff 4.3.0 hf544144_1 conda-forge
libuuid 2.32.1 h7f98852_1000 conda-forge
libvorbis 1.3.7 h9c3ff4c_0 conda-forge
libwebp-base 1.2.1 h7f98852_0 conda-forge
libxcb 1.13 h7f98852_1003 conda-forge
libxkbcommon 1.0.3 he3ba5ed_0 conda-forge
libxml2 2.9.12 h72842e0_0 conda-forge
libzip 1.8.0 h4de3113_1 conda-forge
libzlib 1.2.11 h36c2ea0_1013 conda-forge
logbook 1.5.3 py39h3811e60_4 conda-forge
loguru 0.5.3 py39hf3d152e_2 conda-forge
lz4-c 1.9.3 h9c3ff4c_1 conda-forge
markupsafe 2.0.1 py39h3811e60_0 conda-forge
matplotlib-inline 0.1.3 pyhd8ed1ab_0 conda-forge
mccabe 0.6.1 py_1 conda-forge
mistune 0.8.4 py39h3811e60_1004 conda-forge
mypy_extensions 0.4.3 py39hf3d152e_3 conda-forge
mysql-common 8.0.25 ha770c72_2 conda-forge
mysql-libs 8.0.25 hfa10184_2 conda-forge
nbclient 0.5.4 pyhd8ed1ab_0 conda-forge
nbconvert 6.2.0 py39hf3d152e_0 conda-forge
nbformat 5.1.3 pyhd8ed1ab_0 conda-forge
ncurses 6.2 h58526e2_4 conda-forge
nest-asyncio 1.5.1 pyhd8ed1ab_0 conda-forge
nettle 3.6 he412f7d_0 conda-forge
nlopt 2.7.0 py39h3e08f04_1 conda-forge
nptyping 1.4.4 pyhd8ed1ab_0 conda-forge
nspr 4.30 h9c3ff4c_0 conda-forge
nss 3.69 hb5efdd6_1 conda-forge
numpy 1.21.2 py39hdbf815f_0 conda-forge
numpydoc 1.1.0 py_1 conda-forge
occt 7.5.2 h7391655_1 conda-forge
ocp 7.5.2beta 1_py3.9 cadquery
openexr 2.5.5 hf817b99_0 conda-forge
openh264 2.1.1 h780b84a_0 conda-forge
openjpeg 2.4.0 hb52868f_1 conda-forge
openssl 1.1.1l h7f98852_0 conda-forge
packaging 21.0 pyhd8ed1ab_0 conda-forge
pandoc 2.14.2 h7f98852_0 conda-forge
pandocfilters 1.5.0 pyhd8ed1ab_0 conda-forge
parso 0.7.0 pyh9f0ad1d_0 conda-forge
path 16.2.0 py39hf3d152e_0 conda-forge
path.py 12.5.0 0 conda-forge
pathspec 0.9.0 pyhd8ed1ab_0 conda-forge
pcre 8.45 h9c3ff4c_0 conda-forge
pexpect 4.8.0 pyh9f0ad1d_2 conda-forge
pickleshare 0.7.5 py_1003 conda-forge
pip 21.2.4 pyhd8ed1ab_0 conda-forge
platformdirs 2.3.0 pyhd8ed1ab_0 conda-forge
pluggy 1.0.0 py39hf3d152e_1 conda-forge
proj 7.2.0 h277dcde_2 conda-forge
prompt-toolkit 3.0.20 pyha770c72_0 conda-forge
psutil 5.8.0 py39h3811e60_1 conda-forge
pthread-stubs 0.4 h36c2ea0_1001 conda-forge
ptyprocess 0.7.0 pyhd3deb0d_0 conda-forge
pugixml 1.11.4 h9c3ff4c_0 conda-forge
pycodestyle 2.6.0 pyh9f0ad1d_0 conda-forge
pycparser 2.20 pyh9f0ad1d_2 conda-forge
pydocstyle 6.1.1 pyhd8ed1ab_0 conda-forge
pyflakes 2.2.0 pyh9f0ad1d_0 conda-forge
pygments 2.10.0 pyhd8ed1ab_0 conda-forge
pylint 2.11.1 pyhd8ed1ab_0 conda-forge
pyls-black 0.4.6 pyh9f0ad1d_0 conda-forge
pyls-spyder 0.3.2 pyhd8ed1ab_0 conda-forge
pyopenssl 21.0.0 pyhd8ed1ab_0 conda-forge
pyparsing 2.4.7 pyh9f0ad1d_0 conda-forge
pyqt 5.12.3 py39hf3d152e_7 conda-forge
pyqt-impl 5.12.3 py39h0fcd23e_7 conda-forge
pyqt5-sip 4.19.18 py39he80948d_7 conda-forge
pyqtchart 5.12 py39h0fcd23e_7 conda-forge
pyqtgraph 0.12.2 pyhd8ed1ab_0 conda-forge
pyqtwebengine 5.12.1 py39h0fcd23e_7 conda-forge
pyrsistent 0.17.3 py39h3811e60_2 conda-forge
pysocks 1.7.1 py39hf3d152e_3 conda-forge
python 3.9.7 hb7a2778_3_cpython conda-forge
python-dateutil 2.8.2 pyhd8ed1ab_0 conda-forge
python-jsonrpc-server 0.4.0 pyh9f0ad1d_0 conda-forge
python-language-server 0.36.2 pyhd8ed1ab_0 conda-forge
python_abi 3.9 2_cp39 conda-forge
pytz 2021.1 pyhd8ed1ab_0 conda-forge
pyxdg 0.27 pyhd8ed1ab_0 conda-forge
pyyaml 5.4.1 py39h3811e60_1 conda-forge
pyzmq 22.3.0 py39h37b5a0c_0 conda-forge
qdarkstyle 3.0.2 pyhd8ed1ab_0 conda-forge
qt 5.12.9 hda022c4_4 conda-forge
qtawesome 1.0.3 pyhd8ed1ab_0 conda-forge
qtconsole 5.1.1 pyhd8ed1ab_0 conda-forge
qtpy 1.11.2 pyhd8ed1ab_0 conda-forge
rapidjson 1.1.0 he1b5a44_1002 conda-forge
readline 8.1 h46c0cb4_0 conda-forge
regex 2021.9.30 py39h3811e60_0 conda-forge
requests 2.25.1 pyhd3deb0d_0 conda-forge
rope 0.20.1 pyhd8ed1ab_0 conda-forge
rtree 0.9.7 py39hb102c33_2 conda-forge
secretstorage 3.3.1 py39hf3d152e_0 conda-forge
setuptools 58.0.4 py39hf3d152e_2 conda-forge
six 1.16.0 pyh6c4a22f_0 conda-forge
snowballstemmer 2.1.0 pyhd8ed1ab_0 conda-forge
sortedcontainers 2.4.0 pyhd8ed1ab_0 conda-forge
sphinx 4.2.0 pyh6c4a22f_0 conda-forge
sphinxcontrib-applehelp 1.0.2 py_0 conda-forge
sphinxcontrib-devhelp 1.0.2 py_0 conda-forge
sphinxcontrib-htmlhelp 2.0.0 pyhd8ed1ab_0 conda-forge
sphinxcontrib-jsmath 1.0.1 py_0 conda-forge
sphinxcontrib-qthelp 1.0.3 py_0 conda-forge
sphinxcontrib-serializinghtml 1.1.5 pyhd8ed1ab_0 conda-forge
spyder 4.2.1 py39hf3d152e_3 conda-forge
spyder-kernels 1.10.2 py39hf3d152e_0 conda-forge
sqlite 3.36.0 h9cd32fc_2 conda-forge
tbb 2020.2 h4bd325d_4 conda-forge
tbb-devel 2020.2 h4bd325d_4 conda-forge
testpath 0.5.0 pyhd8ed1ab_0 conda-forge
textdistance 4.2.1 pyhd8ed1ab_0 conda-forge
three-merge 0.1.1 pyh9f0ad1d_0 conda-forge
tk 8.6.11 h27826a3_1 conda-forge
toml 0.10.2 pyhd8ed1ab_0 conda-forge
tomli 1.2.1 pyhd8ed1ab_0 conda-forge
tornado 6.1 py39h3811e60_1 conda-forge
traitlets 5.1.0 pyhd8ed1ab_0 conda-forge
typed-ast 1.4.3 py39h3811e60_0 conda-forge
typing-extensions 3.10.0.2 hd8ed1ab_0 conda-forge
typing_extensions 3.10.0.2 pyha770c72_0 conda-forge
typish 1.9.3 pyhd8ed1ab_0 conda-forge
tzdata 2021b he74cb21_0 conda-forge
ujson 4.2.0 py39he80948d_0 conda-forge
urllib3 1.26.7 pyhd8ed1ab_0 conda-forge
utfcpp 3.2.1 ha770c72_0 conda-forge
vtk 9.0.1 no_osmesa_py39h3e52c05_107 conda-forge
watchdog 2.1.6 py39hf3d152e_0 conda-forge
wcwidth 0.2.5 pyh9f0ad1d_2 conda-forge
webencodings 0.5.1 py_1 conda-forge
wheel 0.37.0 pyhd8ed1ab_1 conda-forge
wrapt 1.12.1 py39h3811e60_3 conda-forge
wurlitzer 3.0.2 py39hf3d152e_0 conda-forge
x264 1!161.3030 h7f98852_1 conda-forge
xorg-kbproto 1.0.7 h7f98852_1002 conda-forge
xorg-libice 1.0.10 h7f98852_0 conda-forge
xorg-libsm 1.2.3 hd9c2040_1000 conda-forge
xorg-libx11 1.7.2 h7f98852_0 conda-forge
xorg-libxau 1.0.9 h7f98852_0 conda-forge
xorg-libxdmcp 1.1.3 h7f98852_0 conda-forge
xorg-libxext 1.3.4 h7f98852_1 conda-forge
xorg-libxt 1.2.1 h7f98852_2 conda-forge
xorg-xextproto 7.3.0 h7f98852_1002 conda-forge
xorg-xproto 7.0.31 h7f98852_1007 conda-forge
xz 5.2.5 h516909a_1 conda-forge
yaml 0.2.5 h516909a_0 conda-forge
yapf 0.31.0 pyhd8ed1ab_0 conda-forge
zeromq 4.3.4 h9c3ff4c_1 conda-forge
zipp 3.5.1 pyhd8ed1ab_0 conda-forge
zlib 1.2.11 h36c2ea0_1013 conda-forge
zstd 1.5.0 ha95c52a_0 conda-forge
```

Using:

Both CQ-editor and plain Python

```
(cadquery) [msivak@t540p cadquery-tests]$ python
Python 3.9.7 | packaged by conda-forge | (default, Sep 29 2021, 19:20:46)
[GCC 9.4.0] on linux
```