debian:debdiff artifact views fail to render (AssertionError)

Internal Server Error: /debian/developers/artifact/2490639/
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/asgiref/sync.py", line 486, in thread_handler
    raise exc_info[1]
  File "/usr/lib/python3/dist-packages/django/core/handlers/exception.py", line 42, in inner
    response = await get_response(request)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/asgiref/sync.py", line 486, in thread_handler
    raise exc_info[1]
  File "/usr/lib/python3/dist-packages/django/core/handlers/base.py", line 253, in _get_response_async
    response = await wrapped_callback(
               ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/asgiref/sync.py", line 448, in __call__
    ret = await asyncio.wait_for(future, timeout=None)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/asyncio/tasks.py", line 442, in wait_for
    return await fut
           ^^^^^^^^^
  File "/usr/lib/python3/dist-packages/asgiref/current_thread_executor.py", line 22, in run
    result = self.fn(*self.args, **self.kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/asgiref/sync.py", line 490, in thread_handler
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/contextlib.py", line 81, in inner
    return func(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/django/views/generic/base.py", line 104, in view
    return self.dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/debusine/web/views/base.py", line 135, in dispatch
    return super().dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/django/views/generic/base.py", line 143, in dispatch
    return handler(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/django/views/generic/detail.py", line 109, in get
    context = self.get_context_data(object=self.object)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/debusine/web/views/artifacts.py", line 148, in get_context_data
    **plugin_view(self.artifact).get_context_data(),
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/debusine/web/views/debdiff.py", line 252, in get_context_data
    assert related_to is not None
           ^^^^^^^^^^^^^^^^^^^^^^
AssertionError

Also:

Internal Server Error: /debian/developers/artifact/2490921/
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/asgiref/sync.py", line 486, in thread_handler
    raise exc_info[1]
  File "/usr/lib/python3/dist-packages/django/core/handlers/exception.py", line 42, in inner
    response = await get_response(request)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/asgiref/sync.py", line 486, in thread_handler
    raise exc_info[1]
  File "/usr/lib/python3/dist-packages/django/core/handlers/base.py", line 253, in _get_response_async
    response = await wrapped_callback(
               ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/asgiref/sync.py", line 448, in __call__
    ret = await asyncio.wait_for(future, timeout=None)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/asyncio/tasks.py", line 442, in wait_for
    return await fut
           ^^^^^^^^^
  File "/usr/lib/python3/dist-packages/asgiref/current_thread_executor.py", line 22, in run
    result = self.fn(*self.args, **self.kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/asgiref/sync.py", line 490, in thread_handler
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/contextlib.py", line 81, in inner
    return func(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/django/views/generic/base.py", line 104, in view
    return self.dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/debusine/web/views/base.py", line 135, in dispatch
    return super().dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/django/views/generic/base.py", line 143, in dispatch
    return handler(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/django/views/generic/detail.py", line 109, in get
    context = self.get_context_data(object=self.object)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/debusine/web/views/artifacts.py", line 148, in get_context_data
    **plugin_view(self.artifact).get_context_data(),
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/debusine/web/views/debdiff.py", line 268, in get_context_data
    debdiff_source_summary = self._summarise_debdiff_source(
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/debusine/web/views/debdiff.py", line 93, in _summarise_debdiff_source
    diff_line_number = file[0][0].diff_line_no - 3
                       ~~~~^^^
IndexError: list index out of range