window.py:597:_update_details:AssertionError when trying to unpair devices from a Nano Receiver

Created by: rathann

Information

• Solaar version (solaar --version or git describe --tags if cloned from this repository): 1.0.4 with #996 applied
• Distribution: Fedora 33
• Kernel version (ex. uname -srmo): 5.9.14-200.fc33.x86_64
• Output of solaar show:

Nano Receiver
  Device path  : /dev/hidraw9
  USB id       : 046d:C534
  Serial       : None
    Firmware   : 29.00.B0015
  Has 2 paired device(s) out of a maximum of 2.
  Has 18 successful pairing(s) remaining.
  Notifications: wireless, software present (0x000900)

  1: Wireless Keyboard MK270
     Device path  : /dev/hidraw10
     WPID         : 4023
     Codename     : MK270
     Kind         : keyboard
     Protocol     : HID++ 2.0
     Polling rate : 20 ms (50Hz)
     Serial number: 00000000
     Battery: unknown (device is offline).

  2: Wireless Mouse M150
     Device path  : /dev/hidraw11
     WPID         : 4022
     Codename     : M150
     Kind         : mouse
     Protocol     : HID++ 2.0
     Polling rate : 8 ms (125Hz)
     Serial number: 00000000
     Battery: unknown (device is offline).

Nano Receiver
  Device path  : /dev/hidraw4
  USB id       : 046d:C52E
  Serial       : 9CAE9170
    Firmware   : 15.00.B0048
  Has 2 paired device(s) out of a maximum of 2.
  Notifications: wireless, software present (0x000900)

  1: ? (101E)
     Device path  : None
     WPID         : 101E
     Codename     : ? (101E)
     Kind         : mouse
     Protocol     : unknown (device is offline)
     Polling rate : 8 ms (125Hz)
     Serial number: 489A0850
     The power switch is located on the (unknown).
     Battery: unknown (device is offline).

  2: ? (200E)
     Device path  : None
     WPID         : 200E
     Codename     : ? (200E)
     Kind         : keyboard
     Protocol     : unknown (device is offline)
     Polling rate : 20 ms (50Hz)
     Serial number: 489A0850
     The power switch is located on the (unknown).
     Battery: unknown (device is offline).

Describe the bug Quoting from downstream bug report:

The error occurred every time I try to unpair on each of the following two receivers. Both sets of keyboard/mouse didn't work so I tried to unpair and then pair the devices again.

Additional context Downstream bug report: Fedora bug 1912132.

Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/solaar/ui/window.py", line 597, in _update_details
    assert selected_device
AssertionError

Local variables in innermost frame:
button: <Gtk.ToggleButton object at 0x7f3d84bb84c0 (GtkToggleButton at 0x55c6d46e55d0)>
visible: True
_read_slow: <function _update_details.<locals>._read_slow at 0x7f3d84ba3820>
_details_items: <function _update_details.<locals>._details_items at 0x7f3d84ba39d0>
_make_text: <function _update_details.<locals>._make_text at 0x7f3d84ba38b0>
_set_details: <function _update_details.<locals>._set_details at 0x7f3d84ba3a60>
selected_device: <Device(1,None,? (101E),489A0850)>