[Crash]: When selecting some NewGRF rail stations, road stops, etc due to changed semantics of SetFocusedWidget

[JGRennison]

Version of OpenTTD

Since #11641

Steps to reproduce

Try to select NewGRF rail stations, road stops, etc

Upload crash files

#0  __pthread_kill_implementation (no_tid=0, signo=6, threadid=140737275480832) at ./nptl/pthread_kill.c:44
#1  __pthread_kill_internal (signo=6, threadid=140737275480832) at ./nptl/pthread_kill.c:78
#2  __GI___pthread_kill (threadid=140737275480832, signo=signo@entry=6) at ./nptl/pthread_kill.c:89
#3  0x00007ffff6f9b476 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#4  0x00007ffff6f817f3 in __GI_abort () at ./stdlib/abort.c:79
#5  0x00007ffff6f8171b in __assert_fail_base
    (fmt=0x7ffff7136130 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x5555561bdb5d "widget != nullptr", file=0x5555561bd8c0 "/home/jgr/openttd/trunk/src/window.cpp", line=490, function=<optimised out>) at ./assert/assert.c:92
#6  0x00007ffff6f92e96 in __GI___assert_fail (assertion=0x5555561bdb5d "widget != nullptr", file=0x5555561bd8c0 "/home/jgr/openttd/trunk/src/window.cpp", line=490, function=0x5555561bd940 "bool Window::SetFocusedWidget(WidgetID)")
    at ./assert/assert.c:101
#7  0x00005555560e308f in Window::SetFocusedWidget(int) (this=this@entry=0x555558429c50, widget_index=widget_index@entry=262165) at /home/jgr/openttd/trunk/src/window.cpp:490
#8  0x00005555560e9bb9 in DispatchLeftClickEvent (click_count=1, y=177, x=228, w=0x555558429c50) at /home/jgr/openttd/trunk/src/window.cpp:645
#9  MouseLoop (mousewheel=<optimised out>, click=<optimised out>) at /home/jgr/openttd/trunk/src/window.cpp:2841
#10 HandleMouseEvents() () at /home/jgr/openttd/trunk/src/window.cpp:2938
#11 0x0000555555c93055 in VideoDriver_SDL_Base::PollEvent() (this=0x5555567088f0) at /home/jgr/openttd/trunk/src/video/sdl2_v.cpp:417
#12 0x0000555555c9cef5 in VideoDriver::Tick() (this=this@entry=0x5555567088f0) at /home/jgr/openttd/trunk/src/video/video_driver.cpp:135
#13 0x0000555555c90d6e in VideoDriver_SDL_Base::LoopOnce() (this=0x5555567088f0) at /home/jgr/openttd/trunk/src/video/sdl2_v.cpp:627
#14 VideoDriver_SDL_Base::LoopOnce() (this=0x5555567088f0) at /home/jgr/openttd/trunk/src/video/sdl2_v.cpp:600
#15 VideoDriver_SDL_Base::MainLoop() (this=0x5555567088f0) at /home/jgr/openttd/trunk/src/video/sdl2_v.cpp:645
#16 0x0000555555f035d8 in openttd_main(int, char**) (argc=<optimised out>, argv=<optimised out>) at /home/jgr/openttd/trunk/src/openttd.cpp:817
#17 0x00007ffff6f82d90 in __libc_start_call_main (main=main@entry=0x5555557cb1b0 <main(int, char**)>, argc=argc@entry=2, argv=argv@entry=0x7fffffffdba8) at ../sysdeps/nptl/libc_start_call_main.h:58
#18 0x00007ffff6f82e40 in __libc_start_main_impl (main=0x5555557cb1b0 <main(int, char**)>, argc=2, argv=0x7fffffffdba8, init=<optimised out>, fini=<optimised out>, rtld_fini=<optimised out>, stack_end=0x7fffffffdb98)
    at ../csu/libc-start.c:392
#19 0x000055555586aa65 in _start ()