[bug] [crash] [std] Mojibake-like (or just unusual, non-ASCII characters) in the track title crash the SNES Tracker Debugger

[KungFuFurby]

Describe the bug
Mojibake-like titles are crashing the SNES Tracker Debugger. Specifically, this is actually caused when setting the window title, as the ultimate cause of the crash is a NSInternalInconsistencyException.

To Reproduce

1. Load a SPC file (any title with a non-ASCII character will probably do the trick).
2. Program immediately crashes.
   Here's the log as far as what happens:

Exception Type:        EXC_CRASH (SIGABRT)
Exception Codes:       0x0000000000000000, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY

Application Specific Information:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid parameter not satisfying: aString != nil'
abort() called
terminating with uncaught exception of type NSException

Application Specific Backtrace 1:
0   CoreFoundation                      0x00007fff2e7b9657 __exceptionPreprocess + 250
1   libobjc.A.dylib                     0x00007fff676355bf objc_exception_throw + 48
2   CoreFoundation                      0x00007fff2e7e27f8 +[NSException raise:format:arguments:] + 88
3   Foundation                          0x00007fff30ed4e7d -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 191
4   AppKit                              0x00007fff2b9fe564 -[NSWindow setTitle:] + 185
5   libSDL2-2.0.0.dylib                 0x0000000101a377c2 Cocoa_SetWindowTitle + 105
6   SPC Debugger                        0x000000010172fdf3 _ZN5BaseD11start_trackEiPKc + 563
7   SPC Debugger                        0x000000010172d86c _ZN5BaseD6reloadEPPci + 748
8   SPC Debugger                        0x000000010172ff4a _ZN5BaseD10prev_trackEv + 58
9   SPC Debugger                        0x000000010175d386 _ZN11Main_Window13receive_eventER9SDL_Event + 1622
10  SPC Debugger                        0x000000010173c63f _ZN8Debugger13handle_eventsEv + 1167
11  SPC Debugger                        0x000000010173c136 _ZN8Debugger3runEv + 262
12  SPC Debugger                        0x0000000101745689 _ZN3App3runEv + 25
13  SPC Debugger                        0x0000000101749d69 main + 249
14  libdyld.dylib                       0x00007fff687ddcc9 start + 1

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib        	0x00007fff6892533a __pthread_kill + 10
1   libsystem_pthread.dylib       	0x00007fff689e1e60 pthread_kill + 430
2   libsystem_c.dylib             	0x00007fff688ac808 abort + 120
3   libc++abi.dylib               	0x00007fff65b0b458 abort_message + 231
4   libc++abi.dylib               	0x00007fff65afc8bf demangling_terminate_handler() + 262
5   libobjc.A.dylib               	0x00007fff676375a9 _objc_terminate() + 96
6   libc++abi.dylib               	0x00007fff65b0a887 std::__terminate(void (*)()) + 8
7   libc++abi.dylib               	0x00007fff65b0d1a2 __cxxabiv1::failed_throw(__cxxabiv1::__cxa_exception*) + 27
8   libc++abi.dylib               	0x00007fff65b0d169 __cxa_throw + 113
9   libobjc.A.dylib               	0x00007fff676356ed objc_exception_throw + 350
10  com.apple.CoreFoundation      	0x00007fff2e7e27f8 +[NSException raise:format:arguments:] + 88
11  com.apple.Foundation          	0x00007fff30ed4e7d -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 191
12  com.apple.AppKit              	0x00007fff2b9fe564 -[NSWindow setTitle:] + 185
13  libSDL2-2.0.0.dylib           	0x0000000101a377c2 Cocoa_SetWindowTitle + 105
14  SPC Debugger                  	0x000000010172fdf3 BaseD::start_track(int, char const*) + 563 (BaseD.cpp:474)
15  SPC Debugger                  	0x000000010172d86c BaseD::reload(char**, int) + 748 (BaseD.cpp:534)
16  SPC Debugger                  	0x000000010172ff4a BaseD::prev_track() + 58 (BaseD.cpp:592)
17  SPC Debugger                  	0x000000010175d386 Main_Window::receive_event(SDL_Event&) + 1622 (Main_Window.cpp:329)
18  SPC Debugger                  	0x000000010173c63f Debugger::handle_events() + 1167 (Debugger.cpp:131)
19  SPC Debugger                  	0x000000010173c136 Debugger::run() + 262 (Debugger.cpp:115)
20  SPC Debugger                  	0x0000000101745689 App::run() + 25 (app.cpp:32)
21  SPC Debugger                  	0x0000000101749d69 main + 249 (main.cpp:25)
22  libdyld.dylib                 	0x00007fff687ddcc9 start + 1

Expected behavior
The SPC file should play normally and without crashing the program due to the tagging.

Example File
BotB 14983 AugustusBlkheart - Längholmen.spc.zip

Desktop:

• OS: Mac OS X Catalina 10.15.7 (self-compiled)
• Version 0.2.2