"Record to Instrument" on empty channel header causes access violation

[alvinhochun]

Steps to reproduce:

1. Run Dn-FamiTracker
2. On the channel header, right-click on the empty space to the right of existing channels (right of DPCM)
3. Select "Record to Instrument"

Tested on 0.5.0.2.

 # Child-SP          RetAddr               Call Site
00 000000ab`a90ff4f8 00007ff7`833bbbdb     Dn_FamiTracker!CSeqConversionDefault::IsReady [D:\a\Dn-FamiTracker\Dn-FamiTracker\Source\SequenceParser.cpp @ 76] 
01 000000ab`a90ff500 00007ff7`833d7d66     Dn_FamiTracker!CFamiTrackerDoc::GetChipType+0x17 [D:\a\Dn-FamiTracker\Dn-FamiTracker\Source\FamiTrackerDoc.cpp @ 4409] 
02 000000ab`a90ff530 00007ff7`834890c8     Dn_FamiTracker!CFamiTrackerView::OnTrackerRecordToInst+0x5e [D:\a\Dn-FamiTracker\Dn-FamiTracker\Source\FamiTrackerView.cpp @ 3793] 
03 (Inline Function) --------`--------     Dn_FamiTracker!_AfxDispatchCmdMsg+0xe5 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\cmdtarg.cpp @ 77] 
04 000000ab`a90ff570 00007ff7`834b3299     Dn_FamiTracker!CCmdTarget::OnCmdMsg+0x264 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\cmdtarg.cpp @ 372] 
05 000000ab`a90ff5c0 00007ff7`8348ceeb     Dn_FamiTracker!CView::OnCmdMsg+0x35 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\viewcore.cpp @ 164] 
06 000000ab`a90ff620 00007ff7`8348df90     Dn_FamiTracker!CWnd::OnCommand+0x87 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\wincore.cpp @ 2801] 
07 000000ab`a90ff6b0 00007ff7`83490107     Dn_FamiTracker!CWnd::OnWndMsg+0x60 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\wincore.cpp @ 2114] 
08 000000ab`a90ff830 00007ff7`83489ad8     Dn_FamiTracker!CWnd::WindowProc+0x3f [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\wincore.cpp @ 2100] 
09 000000ab`a90ff870 00007ff7`8348a530     Dn_FamiTracker!AfxCallWndProc+0x120 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\wincore.cpp @ 265] 
0a 000000ab`a90ff970 00007ffc`a0abef5c     Dn_FamiTracker!AfxWndProc+0x54 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\wincore.cpp @ 417] 
0b 000000ab`a90ff9b0 00007ffc`a0abe684     USER32!UserCallWinProcCheckWow+0x50c
0c 000000ab`a90ffb40 00007ff7`8349ffa6     USER32!DispatchMessageWorker+0x494
0d 000000ab`a90ffbc0 00007ff7`834a0821     Dn_FamiTracker!AfxInternalPumpMessage+0x52 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\thrdcore.cpp @ 183] 
0e 000000ab`a90ffbf0 00007ff7`83662c47     Dn_FamiTracker!CWinThread::Run+0x75 [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\thrdcore.cpp @ 629] 
0f 000000ab`a90ffc30 00007ff7`8361de4e     Dn_FamiTracker!AfxWinMain+0xbf [D:\a\_work\1\s\src\vctools\VC7Libs\Ship\ATLMFC\Src\MFC\winmain.cpp @ 61] 
10 (Inline Function) --------`--------     Dn_FamiTracker!invoke_main+0x21 [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl @ 102] 
11 000000ab`a90ffc70 00007ffc`a1467344     Dn_FamiTracker!__scrt_common_main_seh+0x106 [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl @ 288] 
12 000000ab`a90ffcb0 00007ffc`a241cc91     KERNEL32!BaseThreadInitThunk+0x14
13 000000ab`a90ffce0 00000000`00000000     ntdll!RtlUserThreadStart+0x21