CLI does not print table when scanning signal

[callumforrester]

If I run a scan with a signal as the "motor" (e.g. the exposure time of a detector), it fails to render a table. See logs from P46 below:

2025-01-17 11:06:23,879 - An exception raised in the callback <function BestEffortCallback.__call__ at 0x7f1da7aa7c40> is being suppressed to not interrupt plan execution.  To investigate try setting the BLUESKY_DEBUG_CALLBACKS env to '1'
Traceback (most recent call last):
  File "/venv/lib/python3.11/site-packages/bluesky/callbacks/best_effort.py", line 370, in descriptor
    fields = doc.get("hints", {}).get(obj_name, {})["fields"]
             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^
KeyError: 'fields'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/venv/lib/python3.11/site-packages/bluesky/callbacks/core.py", line 65, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/venv/lib/python3.11/site-packages/bluesky/callbacks/best_effort.py", line 103, in __call__
    super().__call__(name, doc, *args, **kwargs)
  File "/venv/lib/python3.11/site-packages/bluesky/callbacks/mpl_plotting.py", line 80, in __call__
    return CallbackBase.__call__(self, name, doc)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/venv/lib/python3.11/site-packages/event_model/__init__.py", line 191, in __call__
    return self._dispatch(name, doc, validate)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/venv/lib/python3.11/site-packages/event_model/__init__.py", line 199, in _dispatch
    output_doc = getattr(self, name)(doc)
                 ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/venv/lib/python3.11/site-packages/bluesky/callbacks/best_effort.py", line 372, in descriptor
    fields = doc["object_keys"][obj_name]
             ~~~~~~~~~~~~~~~~~~^^^^^^^^^^
KeyError: 'det-drv-acquire_time'

Steps To Reproduce

Steps to reproduce the behaviour:

1. Run a spec_scan with a detector exposure time as the signal

Acceptance Criteria

• Runing a spec_scan with a detector exposure time as the signal produces a table

[callumforrester]

This could also be an upstream issue with bluesky, more investigation is needed