on_app_running ui bug

[Loup-Garou911XD]

Description

if a plugin makes a window inside on_app_running then it errors out in cpp

# ba_meta require api 9
import babase
import bauiv1 as bui

class MyUI(bui.Window):
    def __init__(self):

        self._root_widget = bui.containerwidget(
            size=(10, 10), scale=1.2, transition='in_right', stack_offset=(0, 0)
        )
# ba_meta export babase.Plugin
class EntryPoint(babase.Plugin):
    def on_app_running(self):
        MyUI()

0.675 ba: Error in plugin on_app_running().
Traceback (most recent call last):
  File "/home/loup/github/ballistica/build/prefab/full/linux_x86_64_gui/release/ba_data/python/babase/_plugin.py", line 175, in on_app_running
    plugin.on_app_running()
    ~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/loup/.ballisticakit/mods/test.py", line 25, in on_app_running
    AccountSwitcherUI()
    ~~~~~~~~~~~~~~~~~^^
  File "/home/loup/.ballisticakit/mods/test.py", line 18, in __init__
    self._root_widget = bui.containerwidget(
                        ~~~~~~~~~~~~~~~~~~~^
        size=(self._width, self._height), scale=1.2, transition='in_right', stack_offset=(0, 0)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
RuntimeError: Precondition failed @ python_methods_ui_v1.cc:1282: g_ui_v1 && g_ui_v1->screen_root_widget() != nullptr

solution

it goes away if we add a timer

the app gets to a running state and then it activates an app-mode and asks the mode to do something. ui-v1 gets inited by the classic app mode. So I'd try to run that sort of thing in an on-app-mode-active type callback if possible.
It could maybe make sense for plugins to be informed when app-mode is changing. Since something written for ui-v1 should really only fire when ui-v1 is actually in use.
If squads-mode app-mode rolls around using ui-v2 or whatnot then it'll just fail
-efro

the solution should be to add a callback like that

full discussion on ballistica discord