coregistration GUI does not exit cleanly

[jasmainak]

Describe the bug

If I open the coregistration GUI and it crashes for some reason (e.g., missing subjects_dir), a dangling welcome banner is left which becomes distracting the next time the GUI is opened. One can exit ipython and restart the script, but this might require redoing lengthy computation.

Steps to reproduce

$ unset SUBJECTS_DIR

then in ipython:

>>> from mne.gui import coregistration
>>> coregistration()

Expected results

The welcome banner closes

Actual results☺

Additional information

In [2]: mne.sys_info()
Platform: Linux-3.10.0-1160.76.1.el7.x86_64-x86_64-with-glibc2.10
Python: 3.8.6 | packaged by conda-forge | (default, Oct 7 2020, 19:08:05) [GCC 7.5.0]
Executable: /autofs/space/meghnn_001/users/mjas/anaconda3/envs/mne/bin/python3.8
CPU: x86_64: 64 cores
Memory: 125.4 GB

Exception ignored on calling ctypes callback function: <function _ThreadpoolInfo._find_modules_with_dl_iterate_phdr..match_module_callback at 0x7f8f64346940>
Traceback (most recent call last):
File "/autofs/space/meghnn_001/users/mjas/anaconda3/envs/mne/lib/python3.8/site-packages/threadpoolctl.py", line 400, in match_module_callback
self._make_module_from_path(filepath)
File "/autofs/space/meghnn_001/users/mjas/anaconda3/envs/mne/lib/python3.8/site-packages/threadpoolctl.py", line 515, in _make_module_from_path
module = module_class(filepath, prefix, user_api, internal_api)
File "/autofs/space/meghnn_001/users/mjas/anaconda3/envs/mne/lib/python3.8/site-packages/threadpoolctl.py", line 606, in init
self.version = self.get_version()
File "/autofs/space/meghnn_001/users/mjas/anaconda3/envs/mne/lib/python3.8/site-packages/threadpoolctl.py", line 646, in get_version
config = get_config().split()
AttributeError: 'NoneType' object has no attribute 'split'
mne: 1.4.dev0
numpy: 1.23.0 {unknown linalg bindings}
scipy: 1.5.3
matplotlib: 3.3.3 {backend=Qt5Agg}

sklearn: 0.23.2
numba: Not found
nibabel: 3.2.1
nilearn: 0.7.0
dipy: 1.3.0
openmeeg: Not found
cupy: Not found
pandas: 1.1.5
pyvista: 0.36.1 {OpenGL 4.5.0 NVIDIA 455.45.01 via Quadro P5000/PCIe/SSE2}
pyvistaqt: 0.9.0
ipyvtklink: Not found
vtk: 9.0.1
qtpy: 2.0.1 {PyQt5=5.12.9}
ipympl: Not found
/autofs/space/meghnn_001/users/mjas/anaconda3/envs/mne/lib/python3.8/site-packages/pyqtgraph/colors/palette.py:1: RuntimeWarning: PyQtGraph supports Qt version >= 5.15, but 5.12.9 detected.
from ..Qt import QtGui
pyqtgraph: 0.13.1
pooch: v1.5.2

mne_bids: Not found
mne_nirs: Not found
mne_features: Not found
mne_qt_browser: 0.4.0
mne_connectivity: Not found
mne_icalabel: Not found

[jasmainak]

oops ... opened it on the wrong repo. Will reopen on mne-python

[drammock]

@jasmainak I transferred it, no need to recreate.

[jasmainak]

wooops, sorry too late. Feel free to close one of them. Sorry for the noise.