Fix error spam when adding tabs to TabBar without deselect

[AThousandShips]

Ensures current has a valid value after resizing if deselection is not allowed.

The revert marker being visible for the deselect disabled case is a bit annoying and confusing but is a bit more complex to solve, and unsure how it would affect other things with the default values etc., but worth looking into in the future as well.

MRP:
TabMRP.zip

Note how it will print:

ERROR: Index p_idx = -1 is out of bounds (tabs.size() = 2).
   at: TabBar::ensure_tab_visible (scene/gui/tab_bar.cpp:1555)

When opening the file, and also when resizing the tab bar

This ensures the current value is updated to the correct range in this case

Edit: Confirmed that this works on top of:

• Tweak property order in the inspector for TabBar #88477

[kitbdev]

Works good for changing the tab amount.

The issue can still happen when toggling the tab's disabled property.
Set them all to disabled, set the current to -1, then enable one of the tabs, and the error will occur.
To fix this, a similar change should be made in TabBar::set_tab_disabled().

And it can't be set in the inspector, but we might want to do the same in TabBar::set_tab_hidden() since _can_deselect() also checks that.

[AThousandShips]

Will fix that later today, thank you!

[AThousandShips]

Removed the check for _can_deselect from the ensure_tab_visible, this solves the above errors as well, it doesn't make sense to have that check there as ensuring the visibility of the deselected tab doesn't mean anything regardless of the deselection state

[akien-mga]

Thanks!

[AThousandShips]

Thank you!