report.add_figure bad tags error not specific enough

Describe the bug

The report class complains about a bad tag but does not say what characters are bad. Furthermore, I think it should allow numeric characters. I get:

ValueError: The following tags contained invalid characters: 'Subject 2002'

Steps to reproduce

Just do:

import matplotlib.pyplot as plt
from mne.report import Report

rep = Report()
subject = '2002'
fig = plt.figure()
rep.add_figure(fig, title=f'Figure {i}', tags=(f'Subject {subject}',))

Expected results

Report is produced with tag “subject 2002”

Actual results

Numeric subjects are quite common and I’d imagine a common usecase would be to use numeric tags. I think they should work … did work previously in rep.add_figs_to_section, so I’d consider this a regression.

Additional information

I’m on latest master branch

[jasmainak]

no strong feelings about exposing auto_close. I think if MNE-report creates a figure, it should auto-close, but if user created the figure (as in add_figure), it should not close, by default.

[hoechenberger]

@jasmainak I think this makes sense, yes!