Enabling the allow-kernel-type-selection option breaks the kernels window

[alankeny]

Describe the bug
After upgrading Linux Mint from 22.0 to 22.1, the Linux Kernels window in Update Manager no longer opens while the allow-kernel-type-selection option is enabled.

Screenshots
Not applicable.

To Reproduce
Steps to reproduce the behavior:

1. Upgrade Linux Mint from 22.0 to 22.1.
2. In a terminal execute the command dconf write /com/linuxmint/updates/allow-kernel-type-selection true
3. Launch Update Manager
4. From the View menu, select the Linux Kernels option
5. Update Manager never opens the Kernels window

Expected behavior
The kernels window should open with the option to select a Kernel flavor from a pop-up menu in the lower left corner.

Distribution:

• Linux Mint
• LMDE
• Other (please specify)

Software version:
7.0.5

Logs:
Not applicable, please see crash reports.

Crash report:
First run:

Traceback (most recent call last):
  File "/usr/lib/linuxmint/mintUpdate/mintUpdate.py", line 1900, in on_kernel_menu_activated
    KernelWindow(self.on_kernel_window_closed)
  File "/usr/lib/linuxmint/mintUpdate/kernelwindow.py", line 227, in __init__
    self.kernel_type_combo.append_text(kernel_type[1:])
    ^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'KernelWindow' object has no attribute 'kernel_type_combo'. Did you mean: 'ui_kernel_type_combo'?

After making the suggested change, second run:

Traceback (most recent call last):
  File "/usr/lib/linuxmint/mintUpdate/mintUpdate.py", line 1900, in on_kernel_menu_activated
    KernelWindow(self.on_kernel_window_closed)
  File "/usr/lib/linuxmint/mintUpdate/kernelwindow.py", line 229, in __init__
    self.kernel_type_combo.set_active(index)
    ^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'KernelWindow' object has no attribute 'kernel_type_combo'. Did you mean: 'ui_kernel_type_combo'?

After making the suggested change, third run:

Traceback (most recent call last):
  File "/usr/lib/linuxmint/mintUpdate/mintUpdate.py", line 1900, in on_kernel_menu_activated
    KernelWindow(self.on_kernel_window_closed)
  File "/usr/lib/linuxmint/mintUpdate/kernelwindow.py", line 230, in __init__
    self.ui_kernel_type_combo.connect("changed", on_kernel_type_combo_changed)
                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
NameError: name 'on_kernel_type_combo_changed' is not defined. Did you mean: 'self.on_kernel_type_combo_changed'?

Additional context
After making all three suggested changes, the Kernel window opens and displays the Kernel flavor pop-up menu as expected. I can't speak to the quality of the changes suggested, other than the window opens.

Locale:
Not applicable.

kernelwindow.py.txt

[Wohlstand]

I found the same bug on my end after fresh installation. Actually it's easy to fix. Let me prepare the patch...

[mtwebster]

Fixed by #922