This is zoomed out and hit reset (this might be already fixed in 9024? but since there's an assert I thought it might be helpfull.)

This is Widelands Version bzr9023[widelands] (Debug)
...
4: Ullr: new island exploration - direction: 2
TrainingSite::drop_stalled_soldiers: Kicking somebody out.
widelands: /home/worm/src/widelands/src/graphic/gl/fields_to_draw.cc:109: void FieldsToDraw::reset(const Widelands::EditorGameBase&, const Vector2f&, float, RenderTarget*): Assertion `w_ > 0' failed.

Thread 1 "widelands" received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
51	../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1  0x00007ffff5307801 in __GI_abort () at abort.c:79
#2  0x00007ffff52f739a in __assert_fail_base (fmt=0x7ffff547e7d8 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x5555568c1516 "w_ > 0", file=file@entry=0x5555568c1488 "/home/worm/src/widelands/src/graphic/gl/fields_to_draw.cc", line=line@entry=109, function=function@entry=0x5555568c1640 <FieldsToDraw::reset(Widelands::EditorGameBase const&, Vector2<float> const&, float, RenderTarget*)::__PRETTY_FUNCTION__> "void FieldsToDraw::reset(const Widelands::EditorGameBase&, const Vector2f&, float, RenderTarget*)") at assert.c:92
#3  0x00007ffff52f7412 in __GI___assert_fail (assertion=0x5555568c1516 "w_ > 0", file=0x5555568c1488 "/home/worm/src/widelands/src/graphic/gl/fields_to_draw.cc", line=109, function=0x5555568c1640 <FieldsToDraw::reset(Widelands::EditorGameBase const&, Vector2<float> const&, float, RenderTarget*)::__PRETTY_FUNCTION__> "void FieldsToDraw::reset(const Widelands::EditorGameBase&, const Vector2f&, float, RenderTarget*)") at assert.c:101
#4  0x00005555565eed96 in FieldsToDraw::reset (this=0x55555f22c0d0, egbase=..., viewpoint=..., zoom=-922624, dst=0x55555ecaef90) at /home/worm/src/widelands/src/graphic/gl/fields_to_draw.cc:109
#5  0x00005555565d7496 in MapView::draw_terrain (this=0x55555f22bfb8, egbase=..., dst=0x55555ecaef90) at /home/worm/src/widelands/src/wui/mapview.cc:380
#6  0x000055555631f9fc in InteractivePlayer::draw_map_view (this=0x55555f22beb0, given_map_view=0x55555f22bfb8, dst=0x55555ecaef90) at /home/worm/src/widelands/src/wui/interactive_player.cc:291
#7  0x000055555631f8e3 in InteractivePlayer::draw (this=0x55555f22beb0, dst=...) at /home/worm/src/widelands/src/wui/interactive_player.cc:278
#8  0x000055555626e65c in UI::Panel::do_draw_inner (this=0x55555f22beb0, dst=...) at /home/worm/src/widelands/src/ui_basic/panel.cc:751
#9  0x000055555626e836 in UI::Panel::do_draw (this=0x55555f22beb0, dst=...) at /home/worm/src/widelands/src/ui_basic/panel.cc:784
#10 0x000055555626d092 in UI::Panel::do_run (this=0x55555f22beb0) at /home/worm/src/widelands/src/ui_basic/panel.cc:194
#11 0x0000555555f1925c in UI::Panel::run<UI::Panel::Returncodes> (this=0x55555f22beb0) at /home/worm/src/widelands/src/ui_basic/panel.h:103
#12 0x0000555556065dce in Widelands::Game::run (this=0x7fffffff9ac0, loader_ui=0x7fffffff97c0, start_game_type=Widelands::Game::Loaded, script_to_run="", replay=false, prefix_for_replays="single_player") at /home/worm/src/widelands/src/logic/game.cc:548
#13 0x00005555560650bb in Widelands::Game::run_load_game (this=0x7fffffff9ac0, filename="save/wl_autosave_00.wgf", script_to_run="") at /home/worm/src/widelands/src/logic/game.cc:402
#14 0x0000555555f108fe in WLApplication::load_game (this=0x555556e43f30) at /home/worm/src/widelands/src/wlapplication.cc:1351
#15 0x0000555555f0f6bc in WLApplication::mainmenu_singleplayer (this=0x555556e43f30) at /home/worm/src/widelands/src/wlapplication.cc:1181
#16 0x0000555555f0efd4 in WLApplication::mainmenu (this=0x555556e43f30) at /home/worm/src/widelands/src/wlapplication.cc:1082
#17 0x0000555555f0b3e5 in WLApplication::run (this=0x555556e43f30) at /home/worm/src/widelands/src/wlapplication.cc:454
#18 0x0000555555f0994f in main (argc=1, argv=0x7fffffffdfb8) at /home/worm/src/widelands/src/main.cc:44