generation raised StopIteration

[baylessj]

Describe the bug
sphinx-build exits with a raised exception under normal conditions.

Seems related to #5870 and #5076.

To Reproduce
Run sphinx-build on the project linked below.

Expected behavior
project builds successfully.

Your project
pros-docs

Environment info

• OS: Pop!_OS 19.04
• Python version: 3.7.3
• Sphinx version: 2.2.0
• Sphinx extensions: ['tabs', 'ablog', 'sphinx_click.ext']

Additional context
Log file:

# Sphinx version: 2.2.0
# Python version: 3.7.3 (CPython)
# Docutils version: 0.15.2 release
# Jinja2 version: 2.10.3
# Last messages:
#   writing output... [ 96%] tutorials/topical/multitasking
#   writing output... [ 97%] tutorials/topical/notifications
#   writing output... [ 98%] tutorials/topical/vision
#   writing output... [ 98%] tutorials/topical/wireless-upload
#   writing output... [ 99%] tutorials/walkthrough/clawbot
#   writing output... [100%] tutorials/walkthrough/creating-c-project
#   
#   generating indices...
#   genindex
#   done
# Loaded extensions:
#   sphinx.ext.mathjax (2.2.0) from /home/bayle/.local/lib/python3.7/site-packages/sphinx/ext/mathjax.py
#   sphinxcontrib.applehelp (1.0.1) from /home/bayle/.local/lib/python3.7/site-packages/sphinxcontrib/applehelp/__init__.py
#   sphinxcontrib.devhelp (1.0.1) from /home/bayle/.local/lib/python3.7/site-packages/sphinxcontrib/devhelp/__init__.py
#   sphinxcontrib.htmlhelp (1.0.2) from /home/bayle/.local/lib/python3.7/site-packages/sphinxcontrib/htmlhelp/__init__.py
#   sphinxcontrib.serializinghtml (1.1.3) from /home/bayle/.local/lib/python3.7/site-packages/sphinxcontrib/serializinghtml/__init__.py
#   sphinxcontrib.qthelp (1.0.2) from /home/bayle/.local/lib/python3.7/site-packages/sphinxcontrib/qthelp/__init__.py
#   alabaster (0.7.12) from /home/bayle/.local/lib/python3.7/site-packages/alabaster/__init__.py
#   tabs (unknown version) from /home/bayle/Documents/git/pros-docs/sphinx-tabs/sphinx_tabs/tabs.py
#   ablog (0.9.4) from /usr/local/lib/python3.7/dist-packages/ablog/__init__.py
#   sphinx_click.ext (unknown version) from /home/bayle/.local/lib/python3.7/site-packages/sphinx_click/ext.py
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/ablog/post.py", line 580, in generate_atom_feeds
    raise StopIteration
StopIteration

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

Traceback (most recent call last):
  File "/home/bayle/.local/lib/python3.7/site-packages/sphinx/cmd/build.py", line 276, in build_main
    app.build(args.force_all, filenames)
  File "/home/bayle/.local/lib/python3.7/site-packages/sphinx/application.py", line 346, in build
    self.builder.build_update()
  File "/home/bayle/.local/lib/python3.7/site-packages/sphinx/builders/__init__.py", line 299, in build_update
    len(to_build))
  File "/home/bayle/.local/lib/python3.7/site-packages/sphinx/builders/__init__.py", line 364, in build
    self.finish()
  File "/home/bayle/.local/lib/python3.7/site-packages/sphinx/builders/html.py", line 633, in finish
    self.finish_tasks.add_task(self.gen_pages_from_extensions)
  File "/home/bayle/.local/lib/python3.7/site-packages/sphinx/util/parallel.py", line 42, in add_task
    res = task_func()
  File "/home/bayle/.local/lib/python3.7/site-packages/sphinx/builders/html.py", line 656, in gen_pages_from_extensions
    for pagename, context, template in pagelist:
RuntimeError: generator raised StopIteration

[tk0miya]

I guess you're using an extension not supporting py3 properly. The error was caused in gen_pages_from_extensions event. It is working to generate extra pages for extensions.

  File "/home/bayle/.local/lib/python3.7/site-packages/sphinx/builders/html.py", line 656, in gen_pages_from_extensions
    for pagename, context, template in pagelist:
RuntimeError: generator raised StopIteration

Please check your extensions and report this to them.
Thanks,

[baylessj]

The error was in fact a result of an issue with my project/the Ablog package. This issue is tracked in sunpy/ablog#43.