[Inline Frame] openttd.exe!std::Narrow_char_traits<char,int>::length(const char * const) Line 409 C++
[Inline Frame] openttd.exe!std::string::assign(const char * const) Line 3264 C++
[Inline Frame] openttd.exe!std::string::{ctor}(const char * const) Line 2521 C++
openttd.exe!FoundTownWindow::ExecuteFoundTownCommand(unsigned int tile, bool random, unsigned int errstr, void(*)(const CommandCost &, unsigned int, unsigned int, unsigned int, unsigned int) cc) Line 1165 C++
openttd.exe!FoundTownWindow::OnPlaceObject(Point pt, unsigned int tile) Line 1220 C++
openttd.exe!HandleViewportClicked(const Viewport * vp, int x, int y) Line 2359 C++
openttd.exe!MouseLoop(MouseClick click, int mousewheel) Line 2846 C++
openttd.exe!HandleMouseEvents() Line 2977 C++
openttd.exe!WndProcGdi(HWND_ * hwnd, unsigned int msg, unsigned int64 wParam, int64 lParam) Line 432 C++
[External Code]
openttd.exe!VideoDriver_Win32Base::PollEvent() Line 857 C++
openttd.exe!VideoDriver::Tick() Line 133 C++
openttd.exe!VideoDriver_Win32Base::MainLoop() Line 868 C++
openttd.exe!openttd_main(int argc, char * * argv) Line 802 C++
openttd.exe!WinMain(HINSTANCE * hInstance, HINSTANCE * hPrevInstance, char * lpCmdLine, int nCmdShow) Line 413 C++
[External Code]

20210626-master-gda7621cc55, Windows 10

I don't have access to that nightly via cdn.openttd.org because of #9386. Where did you get that nightly from (more specifically commit da7621c)?

Manual build is the only way.