KeyError: 'data/users/content.json'

Any fix to this?
```
[15:19:44] Site:1DdPHe..Vi9D ContentDb not initialized, load files from filesystem...
[15:19:50] - Unhandled exception: KeyError: 'data/users/content.json' in /greenlet.py line 766 > Site.py line 263 > ContentDbDict.py line 59
Traceback (most recent call last):
File "src/gevent/greenlet.py", line 766, in gevent._greenlet.Greenlet.run
File "/home/ZeroNet/src/Site/Site.py", line 263, in downloadContent
for file_relative_path in list(self.content_manager.contents[inner_path].get("includes", {}).keys()):
File "/home/ZeroNet/src/Content/ContentDbDict.py", line 59, in __getitem__
raise KeyError(key)
KeyError: 'data/users/content.json'
[15:19:50] - Unhandled exception: KeyError: 'data/users/content.json' in /greenlet.py line 766 > Site.py line 203 > ContentDbDict.py line 59
Traceback (most recent call last):
File "src/gevent/greenlet.py", line 766, in gevent._greenlet.Greenlet.run
File "/home/ZeroNet/src/Site/Site.py", line 203, in downloadContent
for file_relative_path in list(self.content_manager.contents[inner_path].get("files", {}).keys()):
File "/home/ZeroNet/src/Content/ContentDbDict.py", line 59, in __getitem__
raise KeyError(key)
KeyError: 'data/users/content.json'
```

Start by tracing the content-loading paths in src/Site/Site.py at lines 203 and 263, then inspect src/Content/ContentDbDict.py at line 59. Reproduce the KeyError for data/users/content.json and determine why the content mapping lacks that key; done means the reported loading path no longer raises this exception and related behavior is covered by tests.

Written by the indexing model from the issue text.