System Information
Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX 1060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 419.17

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-06-17 21:07, hash: rB741641f4c3b8

Short description of error
Crash creating an additional workspace from /+\ workspace tab. It's intermittent in a production build but 100% reproducible here in a debug build (tested with an empty ...\2.80\config dir as well)

Exact steps for others to reproduce the error
Start Blender, and from the /+\ menu in the workspace tab list, select General->Layout.

Blender will often crash at this point. In a debug build it happens every time I try it. VSCode backtrace:

blender.exe!WM_event_get_keymap_from_toolsystem(wmWindowManager * wm, wmEventHandler_Keymap * handler) Line 3663 (g:\bdev\blender\source\blender\windowmanager\intern\wm_event_system.c:3663)
blender.exe!WM_event_get_keymap_from_handler(wmWindowManager * wm, wmEventHandler_Keymap * handler) Line 4912 (g:\bdev\blender\source\blender\windowmanager\intern\wm_event_system.c:4912)
blender.exe!wm_handlers_do_intern(bContext * C, wmEvent * event, ListBase * handlers) Line 2693 (g:\bdev\blender\source\blender\windowmanager\intern\wm_event_system.c:2693)
blender.exe!wm_handlers_do(bContext * C, wmEvent * event, ListBase * handlers) Line 2947 (g:\bdev\blender\source\blender\windowmanager\intern\wm_event_system.c:2947)
blender.exe!wm_event_do_handlers(bContext * C) Line 3390 (g:\bdev\blender\source\blender\windowmanager\intern\wm_event_system.c:3390)
blender.exe!WM_main(bContext * C) Line 420 (g:\bdev\blender\source\blender\windowmanager\intern\wm.c:420)
blender.exe!main(int argc, const unsigned char * * UNUSED_argv_c) Line 502 (g:\bdev\blender\source\creator\creator.c:502)
blender.exe!invoke_main() Line 79 (d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:79)
blender.exe!scrt_common_main_seh() Line 288 (d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288)
blender.exe!scrt_common_main() Line 331 (d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:331)
blender.exe!mainCRTStartup() Line 17 (d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_main.cpp:17)
kernel32.dll!00007ff856894034() (Unknown Source:0)
ntdll.dll!00007ff858a53691() (Unknown Source:0)

Code:

Trap at wm_event_system.c:3663 >

/** Follow #wmEventHandler_KeymapDynamicFn signiture. */
wmKeyMap *WM_event_get_keymap_from_toolsystem(wmWindowManager *wm, wmEventHandler_Keymap *handler)
{
  ScrArea *sa = handler->dynamic.user_data;
  handler->keymap_tool = NULL;
  bToolRef_Runtime *tref_rt = sa->runtime.tool ? sa->runtime.tool->runtime : NULL;
> if (tref_rt && tref_rt->keymap[0]) {

sa->runtime.tool fields are all 0xdd filled or otherwise nonsense at this point.