WME3D: Alpha Polaris - crash when cycling through available shadow types

[lolbot-iichan]

This is not required to complete the game, but may bring similar bugs in other games.

TESTCASE:

1. Start Alpha Polaris
2. Begin first day, click through intro until you gain control over character
3. Press Ctrl+F3 result

EXPECTED RESULT: Game secret combination is used to cycle through various shadow types

ACTUAL RESULT:

Thread 1 received signal SIGSEGV, Segmentation fault.
0x000000014030a492 in Wintermute::BaseSurfaceOpenGL3D::setTexture (
    this=0xbaadf00dbaadf00d)
    at engines/wintermute/base/gfx/opengl/base_surface_opengl3d.cpp:294
294             prepareToDraw();
(gdb) bt
#0  0x000000014030a492 in Wintermute::BaseSurfaceOpenGL3D::setTexture (
    this=0xbaadf00dbaadf00d)
    at engines/wintermute/base/gfx/opengl/base_surface_opengl3d.cpp:294
#1  0x00000001402eddf3 in Wintermute::BaseRenderOpenGL3D::displayShadow (
    this=0x5a314a0, object=0x54ae8650, lightPos=..., lightPosRelative=true)
    at engines/wintermute/base/gfx/opengl/base_render_opengl3d.cpp:214
#2  0x0000000140232adb in Wintermute::AdActor3DX::display (this=0x54ae8650)
    at engines/wintermute/ad/ad_actor_3dx.cpp:385
#3  0x000000014026fd95 in Wintermute::AdScene::displayRegionContent (
    this=0x59465120, region=0x0, display3DOnly=false)
    at engines/wintermute/ad/ad_scene.cpp:1379
#4  0x000000014026f570 in Wintermute::AdScene::traverseNodes (
    this=0x59465120, doUpdate=false)
    at engines/wintermute/ad/ad_scene.cpp:1231
#5  0x000000014026f6b2 in Wintermute::AdScene::display (this=0x59465120)
    at engines/wintermute/ad/ad_scene.cpp:1266
#6  0x000000014025939d in Wintermute::AdGame::displayContent (
    this=0x127cb5b0, doUpdate=true, displayAll=false)
    at engines/wintermute/ad/ad_game.cpp:2126
#7  0x000000014022e7e9 in Wintermute::WintermuteEngine::messageLoop (
    this=0x3179a60) at engines/wintermute/wintermute.cpp:314
#8  0x000000014022deba in Wintermute::WintermuteEngine::run (this=0x3179a60)
    at engines/wintermute/wintermute.cpp:140
#9  0x000000014002b9ff in runGame (plugin=0x2dc94d0, enginePlugin=0x2dc4ca0,
    system=..., debugLevels=...) at base/main.cpp:309
#10 0x000000014002d0a7 in scummvm_main (argc=1, argv=0x2722d30)
    at base/main.cpp:608
#11 0x0000000140029139 in SDL_main (argc=1, argv=0x2722d30)
    at backends/platform/sdl/win32/win32-main.cpp:71
#12 0x0000000140029077 in WinMain ()
    at backends/platform/sdl/win32/win32-main.cpp:54
#13 0x00000001407b19e2 in main (flags=<optimized out>,
    cmdline=<optimized out>, inst=<optimized out>)