Happens on both branches, including 2.19.x with wxWidgets 3.3.1.

VM Region Info: 0x50403020950 is not in any region.  Bytes after previous region: 5033027651921  Bytes before following region: 100038327793328
      REGION TYPE                    START - END         [ VSIZE] PRT/MAX SHRMOD  REGION DETAIL
      mapped file                7020000000-702b2ec000   [178.9M] r--/rwx SM=COW  Object_id=fb1308
--->  GAP OF 0x5f8fd4d14000 BYTES
      Malloc Nano              600000000000-600020000000 [512.0M] rw-/rwx SM=PRV  

Thread 0 Crashed::  Dispatch queue: com.apple.main-thread
0   libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109be76a0 wxDialog::OSXSetWorksWhenModal(bool) + 24
1   libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109b47398 wxDialog::OSXBeginModalDialog() + 60
2   libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109bf06e8 wxMessageDialog::ShowModal() + 348
3   libdcpomatic2-wx.dylib                 0x103ab6e3c error_dialog(wxWindow*, wxString, boost::optional<wxString>) + 232
4   libdcpomatic2-wx.dylib                 0x10394c480 KDMOutputPanel::make(std::__1::list<std::__1::shared_ptr<KDMWithMetadata>, std::__1::allocator<std::__1::shared_ptr<KDMWithMetadata>>>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, std::__1::function<bool (boost::filesystem::path)>) + 4672
5   dcpomatic2_kdm                         0x1024a99c8 DOMFrame::create_kdms() + 1616
6   libwx_baseu-3.2.0.4.1.dylib            0x10b00a830 wxEvtHandler::SearchDynamicEventTable(wxEvent&) + 360
7   libwx_baseu-3.2.0.4.1.dylib            0x10b00a4e4 wxEvtHandler::ProcessEventLocally(wxEvent&) + 88
8   libwx_baseu-3.2.0.4.1.dylib            0x10b00a308 wxEvtHandler::ProcessEvent(wxEvent&) + 56
9   libwx_baseu-3.2.0.4.1.dylib            0x10b00a1a4 wxEvtHandler::SafelyProcessEvent(wxEvent&) + 24
10  libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109b69424 wxButton::OSXHandleClicked(double) + 116
11  AppKit                                 0x19e6c9610 -[NSApplication(NSResponder) sendAction:to:from:] + 540
12  AppKit                                 0x19e6c93c4 -[NSControl sendAction:to:] + 88
13  AppKit                                 0x19e6c92f8 __26-[NSCell _sendActionFrom:]_block_invoke + 100
14  AppKit                                 0x19e6c9220 -[NSCell _sendActionFrom:] + 204
15  AppKit                                 0x19e6c911c -[NSButtonCell _sendActionFrom:] + 96
16  AppKit                                 0x19e6c6684 NSControlTrackMouse + 1540
17  AppKit                                 0x19e6c6054 -[NSCell trackMouse:inRect:ofView:untilMouseUp:] + 144
18  AppKit                                 0x19e6c5f1c -[NSButtonCell trackMouse:inRect:ofView:untilMouseUp:] + 232
19  AppKit                                 0x19ec43118 -[NSControl(_NSTracking) _mouseDown:] + 544
20  AppKit                                 0x19ec42ecc -[NSControl(_NSTracking) mouseDown:] + 128
21  libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109c04758 wxWidgetCocoaImpl::mouseEvent(NSEvent*, NSView*, void*) + 256
22  AppKit                                 0x19f003ed0 -[NSWindow _handleLeftMouseDownEvent:isDelayedEvent:] + 4244
23  AppKit                                 0x19e652ef8 -[NSWindow(NSEventRouting) _reallySendEvent:isDelayedEvent:] + 496
24  AppKit                                 0x19e652b70 -[NSWindow(NSEventRouting) sendEvent:] + 304
25  libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109bf1ff8 -[wxNSWindow sendEvent:] + 116
26  AppKit                                 0x19eda2dac -[NSApplication(NSEventRouting) sendEvent:] + 1296
27  libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109b4491c -[wxNSApplication sendEvent:] + 84
28  AppKit                                 0x19e8c8d48 -[NSApplication _handleEvent:] + 60
29  AppKit                                 0x19e51f95c -[NSApplication run] + 476
30  libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109be9a14 wxGUIEventLoop::OSXDoRun() + 140
31  libwx_baseu-3.2.0.4.1.dylib            0x10afe55c4 wxCFEventLoop::DoRun() + 40
32  libwx_baseu-3.2.0.4.1.dylib            0x10af44cf0 wxEventLoopBase::Run() + 200
33  libwx_baseu-3.2.0.4.1.dylib            0x10af17108 wxAppConsoleBase::MainLoop() + 208
34  libwx_osx_cocoau_core-3.2.0.4.1.dylib          0x109b89d84 wxApp::OnRun() + 36
35  libwx_baseu-3.2.0.4.1.dylib            0x10af746d4 wxEntry(int&, wchar_t**) + 104
36  dcpomatic2_kdm                         0x10249de7c main + 24
37  dyld                                   0x199adfe80 start + 6688

Hopefully fixed by 9e93b20b8b98494d48851004ca5a49b26bbe1833 and by updating wxWidgets and building the Golden Gate version with SDK 26.5.

Reported as still crashing in the 2.18.51 golden gate build (the rasterizeImageUsingScaleFactor crash) on 27.0.1. OP sent a new crash report by email.

Had a second email reporter when using the disk writer 2.18.51 on 27.0.1.