"icon_links" required in html_theme_options in v0.13.0

[valentinsulzer]

Building docs without the "icon_links" key in html_theme_options gives an error. I guess it's related to #1209

Running Sphinx v5.3.0
making output directory... done
loading intersphinx inventory from https://docs.python.org/3/objects.inv...
loading intersphinx inventory from https://www.sphinx-doc.org/en/master/objects.inv...
loading intersphinx inventory from https://numpy.org/doc/stable/objects.inv...
loading intersphinx inventory from https://docs.scipy.org/doc/scipy/objects.inv...
loading intersphinx inventory from https://matplotlib.org/objects.inv...
intersphinx inventory has moved: https://matplotlib.org/objects.inv -> https://matplotlib.org/stable/objects.inv
myst v0.18.1: MdParserConfig(commonmark_only=False, gfm_only=False, enable_extensions=[], disable_syntax=[], all_links_external=False, url_schemes=('http', 'https', 'mailto', 'ftp'), ref_domains=None, highlight_code_blocks=True, number_code_blocks=[], title_to_header=False, heading_anchors=None, heading_slug_func=None, footnote_transition=True, words_per_minute=200, sub_delimiters=('{', '}'), linkify_fuzzy_links=True, dmath_allow_labels=True, dmath_allow_space=True, dmath_allow_digits=True, dmath_double_inline=False, update_mathjax=True, mathjax_classes='tex2jax_process|mathjax_process|math|output_area')

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/pybamm/envs/2738/lib/python3.8/site-packages/sphinx/events.py", line 94, in emit
    results.append(listener.handler(self.app, *args))
  File "/home/docs/checkouts/readthedocs.org/user_builds/pybamm/envs/2738/lib/python3.8/site-packages/pydata_sphinx_theme/__init__.py", line 202, in update_config
    theme_options["icon_links"].insert(
KeyError: 'icon_links'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/pybamm/envs/2738/lib/python3.8/site-packages/sphinx/cmd/build.py", line 276, in build_main
    app = Sphinx(args.sourcedir, args.confdir, args.outputdir,
  File "/home/docs/checkouts/readthedocs.org/user_builds/pybamm/envs/2738/lib/python3.8/site-packages/sphinx/application.py", line 262, in __init__
    self._init_builder()
  File "/home/docs/checkouts/readthedocs.org/user_builds/pybamm/envs/2738/lib/python3.8/site-packages/sphinx/application.py", line 335, in _init_builder
    self.events.emit('builder-inited')
  File "/home/docs/checkouts/readthedocs.org/user_builds/pybamm/envs/2738/lib/python3.8/site-packages/sphinx/events.py", line 105, in emit
    raise ExtensionError(__("Handler %r for event %r threw an exception") %
sphinx.errors.ExtensionError: Handler <function update_config at 0x7f0333cb1430> for event 'builder-inited' threw an exception (exception: 'icon_links')

Extension error (pydata_sphinx_theme):
Handler <function update_config at 0x7f0333cb1430> for event 'builder-inited' threw an exception (exception: 'icon_links')

[bryevdv]

Also encountering this with an update to 0.13

[choldgraf]

closed by #1231

will cut a patch release so y'all stop hitting this!