Reproduce:

• Open Browser
• Right click a URL on the default home page
• Select Download

Log:

Browser(27): Web::EventHandler: Clicking on a link to file:///res/html/misc/padding-inline.html
ProtocolServer(28): StartDownload: No protocol handler for URL: 'file:///res/html/misc/padding-inline.html'
USERSPACE(27) ASSERTION FAILED: m_download
../Applications/Browser/DownloadWidget.cpp:61
[Browser(27:27)]: Terminating Browser(27) due to signal 6
[FinalizerTask(3:3)]: 0xdeadc0de  Kernel::Processor::switch_context(Kernel::Thread*&, Kernel::Thread*&) +181
0xdeadc0de  Kernel::Scheduler::context_switch(Kernel::Thread*) +171
0xdeadc0de  Kernel::Scheduler::pick_next() +870
0xdeadc0de  Kernel::Processor::check_invoke_scheduler() +125
0xdeadc0de  Kernel::Thread::die_if_needed() +189
0xdeadc0de  syscall_handler +2197
0xdeadc0de  syscall_asm_entry +49
0x02f8eaa7
0x02f86399
0x02f86d01
0x0372ec68
0x03736f81
0x032e1b0d
0x03377d94
0x03379a95
0x032f5f73
0x0337ab61
0x030193b2
0x03019adf
0x0300dbb1
0x0300dea7
0x032e4464
0x03726eb8
0x0372715e
0x0dc151eb

[FinalizerTask(3:3)]: Generating coredump for pid: 27
[FinalizerTask(3:3)]: RTC: Year: 2021, month: 1, day: 3, hour: 12, minute: 18, second: 41
CrashDaemon(19): New coredump file: /tmp/coredump/Browser_27_1609676321
CrashDaemon(19): 0x02f8ea2b: [libc.so] kill +0x1c (Syscall.h:479)
CrashDaemon(19): 0x02f8eaa7: [libc.so] raise +0x20 (signal.cpp:54)
CrashDaemon(19): 0x02f86399: [libc.so] abort +0x19 (stdlib.cpp:230)
CrashDaemon(19): 0x02f86d01: [libc.so] tolower +0x0 (assert.cpp:51)
CrashDaemon(19): 0x0372ec68: [/bin/Browser] Browser::DownloadWidget::DownloadWidget(AK::URL const&) +0x346 (DownloadWidget.cpp:60)
CrashDaemon(19): 0x03736f81: [/bin/Browser] Browser::start_download(AK::URL const&) +0x156 (Atomic.h:158)
CrashDaemon(19): 0x032e1b0d: [libgui.so] GUI::Action::activate(Core::Object*) +0x143 (Atomic.h:257)
CrashDaemon(19): 0x03377d94: [libgui.so] GUI::WindowServerConnection::handle(Messages::WindowClient::MenuItemActivated const&) +0x56 (WindowServerConnection.cpp:275)
CrashDaemon(19): 0x03379a95: [libgui.so] .L134 +0x7 (WindowClientEndpoint.h:2220)
CrashDaemon(19): 0x032f5f73: [libgui.so] IPC::Connection<WindowClientEndpoint, WindowServerEndpoint>::handle_messages() +0x7b (OwnPtr.h:192)
CrashDaemon(19): 0x0337ab61: [libgui.so] AK::Function<void ()>::CallableWrapper<IPC::Connection<WindowClientEndpoint, WindowServerEndpoint>::Connection(WindowClientEndpoint&, AK::NonnullRefPtr<Core::LocalSocket>)::{lambda()#2}>::call() const +0x27 (Function.h:101)
CrashDaemon(19): 0x030193b2: [libcore.so] Core::Notifier::event(Core::Event&) +0x4e (Notifier.cpp:74)
CrashDaemon(19): 0x03019adf: [libcore.so] Core::Object::dispatch_event(Core::Event&, Core::Object*) +0x59 (Object.h:104)
CrashDaemon(19): 0x0300dbb1: [libcore.so] Core::EventLoop::pump(Core::EventLoop::WaitMode) +0x1dd (Atomic.h:257)
CrashDaemon(19): 0x0300dea7: [libcore.so] Core::EventLoop::exec() +0x6b (EventLoop.cpp:351)
CrashDaemon(19): 0x032e4464: [libgui.so] GUI::Application::exec() +0x32 (Application.cpp:118)
CrashDaemon(19): 0x03726eb8: [/bin/Browser] main +0x992 (main.cpp:241)
CrashDaemon(19): 0x0372715e: [/bin/Browser] _start +0x42 (crt0_shared.cpp:60)
WindowServer(15): Decoding a ShareableBitmap with shbuf_id=95, size=[16x16]