SegFault in stl_tree library when wiggle around play panel's position slider a lot while play engaged

on 3.0-dev ea2cb6428 I was wiggling around the play panel slider a lot while play was engaged on My_First_Score, and I managed to segfault with the following stack trace:

1 _ZN9__gnu_cxx13new_allocatorISt13_Rb_tree_nodeISt4pairIKiN2Ms10NPlayEventEEEE9constructIS6_IRKS6_EEEvPT_DpOT0_ new_allocator.h 120 0xdaa072
2 std::allocator_traits>>>::_S_construct const&>>(std::allocator>>&, std::allocator_traits>>>::__construct_helper *, (std::pair const&>&&)...) alloc_traits.h 253 0xe16947
3 std::allocator_traits>>>::construct const&>>(std::allocator>>&, std::pair const&> *, (std::pair const&>&&)...) alloc_traits.h 399 0xe16a1f
4 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_create_node const&> stl_tree.h 421 0xe65a22
5 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_clone_node stl_tree.h 445 0xe6588c
6 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_copy stl_tree.h 1207 0xe65e8e
7 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_copy stl_tree.h 1213 0xe65ec8
8 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_copy stl_tree.h 1213 0xe65ec8
9 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_copy stl_tree.h 1213 0xe65ec8
10 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_copy stl_tree.h 1223 0xe65f3c
11 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_copy stl_tree.h 1213 0xe65ec8
12 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_copy stl_tree.h 1213 0xe65ec8
13 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_M_copy stl_tree.h 1213 0xe65ec8
14 std::_Rb_tree, std::_Select1st>, std::less, std::allocator>>::_Rb_tree stl_tree.h 676 0xe66104
15 std::multimap::multimap stl_multimap.h 181 0xe7e209
16 Ms::EventMap::EventMap event.h 314 0xcf5839
17 Ms::Seq::updateSynthesizerState seq.cpp 1522 0x4db6f3
18 Ms::Seq::setPos seq.cpp 1043 0x4d9b63
19 Ms::Seq::processMessages seq.cpp 568 0x4d7b56
20 Ms::Seq::process seq.cpp 730 0x4d84c2

It should be noted that those stl_tree stuff is all standard library stuff, so I'm wondering if it is possible that there is a bug in the implementation (I'm on Windows 10).

Anyway, the bottom part of the musescore end is in Seq::updateSynthesizerState() when

      // Making a local copy of events to avoid touching it
      // from different threads at the same time
      EventMap ev = events;

And that EventMap is a std::multimap:

class EventMap : public std::multimap {};

I can't seem to reproduce it...might have been a rare event. I'm just filing here now in case I run into it again.