BUG color map for get_usage_plot exausted

[wabscale]

│Running visuals job - 2023-04-23 15:36:19.748654                                                                                                                                                                  │
│ Traceback (most recent call last):                                                                                                                                                                                │
│   File "/opt/app/anubis/jobs/visuals.py", line 45, in <module>                                                                                                                                                    │
│     main()                                                                                                                                                                                                        │
│   File "/opt/app/anubis/utils/data.py", line 325, in wrapper                                                                                                                                                      │
│     return function(*args, **kwargs)                                                                                                                                                                              │
│   File "/opt/app/anubis/jobs/visuals.py", line 19, in main                                                                                                                                                        │
│     get_usage_plot(course.id)                                                                                                                                                                                     │
│   File "/usr/local/lib/python3.10/site-packages/flask_caching/__init__.py", line 877, in decorated_function                                                                                                       │
│     rv = self._call_fn(f, *args, **kwargs)                                                                                                                                                                        │
│   File "/usr/local/lib/python3.10/site-packages/flask_caching/__init__.py", line 180, in _call_fn                                                                                                                 │
│     return ensure_sync(fn)(*args, **kwargs)                                                                                                                                                                       │
│   File "/opt/app/anubis/utils/visuals/usage.py", line 55, in get_usage_plot                                                                                                                                       │
│     color = assignment_colors[assignment.id]                                                                                                                                                                      │
│ KeyError: '479a1685-8f26-4eb0-aeeb-116b0727b8c2'                  

[wabscale]

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