BUG: preset formatting should be more error tolerant

[tangkong]

Current Behavior

pcdsdevices/pcdsdevices/epics_motor.py

Line 178 in e1be5bf

Preset position: {self.presets.state()}

this should refer to the "ERROR" preset and display the status instead of exploding

Also in this case the state repr fails:

In [2]: lib_y.presets.state()
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [2], in <cell line: 1>()
----> 1 lib_y.presets.state()

File /cds/group/pcds/pyps/apps/hutch-python/xcs/dev/devpath/pcdsdevices/interface.py:1301, in Presets.state(self)
   1299 state_name = method_name.replace('wm_', '', 1)
   1300 wm_state = getattr(device, method_name)
-> 1301 diff = abs(wm_state())
   1302 if diff < closest:
   1303     state = state_name

File /cds/group/pcds/pyps/apps/hutch-python/xcs/dev/devpath/pcdsdevices/interface.py:1263, in Presets._make_wm_pre.<locals>.wm_pre(self)
   1251 """
   1252 Check the offset from the {} preset position.
   1253
   (...)
   1259     is in the positive direction from us.
   1260 """
   1262 pos = self.presets._cache[preset_type][name]['value']
-> 1263 return pos - self.wm()

TypeError: unsupported operand type(s) for -: 'float' and 'NoneType'

Expected Behavior

Error presets don't crash everything

Context / environment

From debugging some issues in XCS

Steps to Reproduce (for bugs)

slack thread

1. Initialize an IMS motor
2. Somehow don't let its readback callback complete (such that self.position == None)
3. motor.presets.state()

Suggested Solution

Fix it?