missing EXPRESS-G diagram

- go to https://rawgit2.com/bSI-InfraRoom/IFC-Documentation/main/4_3_0_0/rc4/HTML/schema/ifcsharedbldgelements/lexical/ifcbeamstandardcase.htm
- scroll to the bottom
- click EXPRESS Specification to open the text
- click on the link EXPRESS-G diagram (https://rawgit2.com/bSI-InfraRoom/IFC-Documentation/main/4_3_0_0/rc4/HTML/annex/annex-d/ifcsharedbldgelements/diagram_0000.htm)

This file is missing:
- rawgit2 returns just `error`.
- a production deployment like https://standards.buildingsmart.org/IFC/DEV/IFC4_3/RC1/HTML/schema/ifcsharedbldgelements/lexical/ifcbeamstandardcase.htm returns
```
Not Found
The requested URL was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
```

Start by comparing the linked IFCBeamStandardCase page and its EXPRESS-G diagram link in the generated HTML documentation. Check why diagram_0000.htm is unavailable at both the rawgit2 and production URLs. Done means the EXPRESS-G diagram link resolves to the expected diagram instead of an error or 404.

Written by the indexing model from the issue text.