UBSAN complaint in TapDance (running simulation-tests)

[hardenedapple]

Describe the bug
While running simulator tests with UBSAN I get a warning with the stack trace at the end of this post.
This happens in the simulator tests issues/{980,571,806,922} and TapDance/basic.

On running in the debugger It looks like the cause is in getting an address from an empty event_queue_.
This data does end up going into user callback tapDanceAction, which seems to get bad information.

I "got rid of the warning" with the below, but don't know if that makes semantic sense.

diff --git
a/plugins/Kaleidoscope-TapDance/src/kaleidoscope/plugin/TapDance.cpp
b/plugins/Kaleidoscope-TapDance/src/kaleidoscope/plugin/TapDance.cpp
index 999485b0..3fff2eba 100644
--- a/plugins/Kaleidoscope-TapDance/src/kaleidoscope/plugin/TapDance.cpp
+++ b/plugins/Kaleidoscope-TapDance/src/kaleidoscope/plugin/TapDance.cpp
@@ -107,7 +107,7 @@ EventHandlerResult
TapDance::onKeyswitchEvent(KeyEvent &event) {
  if (event_queue_.isEmpty() && !isTapDanceKey(event.key))
    return EventHandlerResult::OK;

-  KeyAddr td_addr = event_queue_.addr(0);
+  KeyAddr td_addr = event_queue_.isEmpty() ? event.addr :
event_queue_.addr(0);
  Key td_key      = Layer.lookupOnActiveLayer(td_addr);
  uint8_t td_id   = td_key.getRaw() - ranges::TD_FIRST;

     #0 0x55978b3ad2c5 in kaleidoscope::Layer_::lookupOnActiveLayer(kaleidoscope::MatrixAddr<(unsigned char)4, (unsigned char)16>) ... src/kaleidoscope/layers.h:103
     #1 0x55978b3c49dd in kaleidoscope::plugin::TapDance::onKeyswitchEvent(kaleidoscope::KeyEvent&) ...plugins/Kaleidoscope-TapDance/src/kaleidoscope/plugin/TapDance.cpp:111
     #2 0x55978b3ab9f9 in kaleidoscope_internal::EventHandler_onKeyswitchEvent_v1_caller<true, kaleidoscope::plugin::TapDance, kaleidoscope::KeyEvent&>::call(kaleidoscope::plugin::TapDance&, kaleidoscope::KeyEvent&) ...tests/issues/423/423.ino:69
     #3 0x55978b3ab31b in kaleidoscope::EventHandlerResult kaleidoscope_internal::EventHandler_onKeyswitchEvent_v1::call<kaleidoscope::plugin::TapDance, kaleidoscope::KeyEvent&>(kaleidoscope::plugin::TapDance&, kaleidoscope::KeyEvent&) ...tests/issues/423/423.ino:69
     #4 0x55978b3aa954 in kaleidoscope::EventHandlerResult kaleidoscope_internal::EventDispatcher::apply<kaleidoscope_internal::EventHandler_onKeyswitchEvent_v1, kaleidoscope::KeyEvent&>(kaleidoscope::KeyEvent&) ...tests/issues/423/423.ino:69

Environment (please complete the following information):

• OS: Linux
• Version master-branch
• Device Virtual

[gedankenexperimenter]

At first glance, I thought using event.addr was probably the wrong choice if the queue was empty, but on closer inspection, I recognized that this initial reaction was incorrect, because the event in question is a TapDance key that toggled on, and the call to tapDanceAction() on line 132 could get the incorrect address and trigger a bug. The suggested fix looks correct to me.