Segmentation fault in qml debugger

Setting a breakpoint in javascript code that imports mjs module(s) leads to the following segmentation fault:.

1  QV4::Runtime::TypeofValue::call          qv4runtime.cpp            1631 0x7ffff762e570 
2  collectProperty                          qv4scopedvalue_p.h        242  0x7ffff016854f 
3  QV4DataCollector::collectAsJson          qv4datacollector.h        78   0x7ffff0168e2e 
4  QV4DataCollector::collectProperties      qv4datacollector.cpp      385  0x7ffff0168fe7 
5  QV4DataCollector::lookupRef              qv4datacollector.cpp      198  0x7ffff01691bd 
6  QV4DataCollector::collectScope           qv4datacollector.cpp      240  0x7ffff01699e0 
7  ScopeJob::run                            qv4debugjob.cpp           184  0x7ffff016b416 
8  QV4Debugger::pauseAndWait                qv4debugger.cpp           278  0x7ffff0164a5e 
9  QV4Debugger::pauseAndWait                qv4debugger.cpp           269  0x7ffff0165cd1 
10 QV4Debugger::maybeBreakAtInstruction     qv4debugger.cpp           209  0x7ffff0165cd1 
11 debug_slowPath                           qv4vme_moth.cpp           291  0x7ffff7619382 
12 QV4::Moth::VME::interpret                qv4vme_moth.cpp           1386 0x7ffff76194b9 
13 QV4::Moth::VME::exec                     qv4vme_moth.cpp           466  0x7ffff761f3d0 
14 QV4::ArrowFunction::virtualCall          qv4functionobject.cpp     528  0x7ffff75b24f8 
15 QV4::FunctionObject::call                qv4functionobject_p.h     202  0x7ffff761c8a3 
16 QV4::Moth::VME::interpret                qv4vme_moth.cpp           757  0x7ffff761c8a3 
17 QV4::Moth::VME::exec                     qv4vme_moth.cpp           466  0x7ffff761f3d0 
18 QV4::Module::evaluate                    qv4module.cpp             125  0x7ffff762347b 
19 QQmlScriptData::scriptValueForContext    qqmlscriptdata.cpp        130  0x7ffff76b3bfd 
20 QQmlScriptData::scriptValueForContext    qqmlscriptdata.cpp        151  0x7ffff76b3c4d 
21 QQmlObjectCreator::create                qqmlobjectcreator.cpp     198  0x7ffff7757133 
22 QQmlComponentPrivate::beginCreate        qscopedpointer.h          116  0x7ffff76e3712 
23 QQmlComponent::create                    qqmlcomponent.cpp         818  0x7ffff76e412e 
24 QQmlApplicationEnginePrivate::finishLoad qqmlapplicationengine.cpp 148  0x7ffff774844a 
25 QQmlApplicationEnginePrivate::startLoad  qqmlapplicationengine.cpp 132  0x7ffff7748aac 
26 QQmlApplicationEngine::load              qqmlapplicationengine.cpp 279  0x7ffff7748b41 
27 main                                     main.cpp                  19   0x555555556774 
  

Analysis had shown that the reason is invalid Value being appended to the list in QV4DataCollector::collectScope() because the loop here accesses beyond context local variables array bounds.

Steps to reproduce:

Open the project in the attached qmldebug_crash.zip archive in qtcreator, set a breakpoint on line 6 in module2.mjs and start debugging (F5). As soon as breakpoint is hit, there will be segmentation fault in C++ code.

See the attached qmldebug_fix_localvars_count.patch for what fixes the issue for me, however, I am not sure that's a proper fix given that it excludes imported modules from the list of local variables shown in the debugger.

I am hitting the issue on Ubuntu 22.04.3 with Qt coming with the distro, however I believe all patforms and 5.x/6.x versions are affected.