Accessing singleton QML type via multiple test cases causes segfault

~/Qt/5.10.1/clang_64/bin/qmake CONFIG+=debug
make
./singletonbug

(lldb) target create "./singletonbug"
warning: (x86_64) /Users/forest/Qt/5.10.1/clang_64/lib/QtQuickTest.framework/Versions/5/QtQuickTest empty dSYM file detected, dSYM was created with an executable with no debug info.
warning: (x86_64) /Users/forest/Qt/5.10.1/clang_64/lib/QtTest.framework/Versions/5/QtTest empty dSYM file detected, dSYM was created with an executable with no debug info.
warning: (x86_64) /Users/forest/Qt/5.10.1/clang_64/lib/QtCore.framework/Versions/5/QtCore empty dSYM file detected, dSYM was created with an executable with no debug info.
warning: 'QtCore' contains a debug script. To run this script in this debug session:

    command script import "/Users/forest/Qt/5.10.1/clang_64/lib/QtCore.framework.dSYM/Contents/Resources/DWARF/../Python/QtCore.py"

To run all discovered debug scripts in this session:

    settings set target.load-script-from-symbol-file true

warning: (x86_64) /Users/forest/Qt/5.10.1/clang_64/lib/QtWidgets.framework/Versions/5/QtWidgets empty dSYM file detected, dSYM was created with an executable with no debug info.
warning: (x86_64) /Users/forest/Qt/5.10.1/clang_64/lib/QtGui.framework/Versions/5/QtGui empty dSYM file detected, dSYM was created with an executable with no debug info.
warning: (x86_64) /Users/forest/Qt/5.10.1/clang_64/lib/QtQml.framework/Versions/5/QtQml empty dSYM file detected, dSYM was created with an executable with no debug info.
warning: (x86_64) /Users/forest/Qt/5.10.1/clang_64/lib/QtNetwork.framework/Versions/5/QtNetwork empty dSYM file detected, dSYM was created with an executable with no debug info.
warning: (x86_64) /Users/forest/Qt/5.10.1/clang_64/lib/QtQuick.framework/Versions/5/QtQuick empty dSYM file detected, dSYM was created with an executable with no debug info.
Current executable set to './singletonbug' (x86_64).
(lldb) env DYLD_IMAGE_SUFFIX=_debug
(lldb) run
Process 22662 launched: './singletonbug' (x86_64)
********* Start testing of all *********
Config: Using QtTest library 5.10.1, Qt 5.10.1 (x86_64-little_endian-lp64 shared (dynamic) debug build; by Clang 8.1.0 (clang-802.0.42) (Apple))
PASS   : all::A::initTestCase()
QDEBUG : all::A::test_the_thing() qml: *** DOING THE THING ***
QDEBUG : all::A::test_the_thing() qml: MySingleton MySingleton(0x102fa5260)
PASS   : all::A::test_the_thing()
PASS   : all::A::cleanupTestCase()
PASS   : all::B::initTestCase()
QDEBUG : all::B::test_the_thing() qml: *** DOING THE THING ***
Process 22662 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
    frame #0: 0x0000000101bcd695 QtQml_debug`QQmlData::get(object=0x0000000102fa5260, create=true) at qqmldata_p.h:243
Target 0: (singletonbug) stopped.
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
  * frame #0: 0x0000000101bcd695 QtQml_debug`QQmlData::get(object=0x0000000102fa5260, create=true) at qqmldata_p.h:243
    frame #1: 0x0000000101ee5a96 QtQml_debug`QQmlData::ensurePropertyCache(engine=0x00007fff5fbfecf8, object=0x0000000102fa5260) at qqmldata_p.h:275
    frame #2: 0x0000000101f62046 QtQml_debug`QQmlType::SingletonInstanceInfo::init(this=0x0000000102e00800, e=0x00007fff5fbfecf8) at qqmlmetatype.cpp:274
    frame #3: 0x000000010201288b QtQml_debug`QV4::QQmlTypeWrapper::get(m=0x000000010c36f7e0, name=0x000000010c36f2f8, hasProperty=0x0000000000000000) at qqmltypewrapper.cpp:188
    frame #4: 0x0000000101cf7f01 QtQml_debug`QV4::Object::get(this=0x000000010c36f7e0, name=0x000000010c36f2f8, hasProperty=0x0000000000000000) const at qv4object_p.h:380
    frame #5: 0x0000000101f14e19 QtQml_debug`QV4::RuntimeHelpers::objectDefaultValue(object=0x000000010c36f7e0, typeHint=1) at qv4runtime.cpp:431
    frame #6: 0x0000000101cf8ef5 QtQml_debug`QV4::RuntimeHelpers::toPrimitive(value=0x000000010c36f7e0, typeHint=0) at qv4runtime_p.h:126
    frame #7: 0x0000000101f15788 QtQml_debug`QV4::convert_to_string_add(engine=0x00000001030a0200, value=0x000000010c36f7e0) at qv4runtime.cpp:525
    frame #8: 0x0000000101f11efc QtQml_debug`QV4::Runtime::method_addString(engine=0x00000001030a0200, left=0x000000010c36f780, right=0x000000010c36f778) at qv4runtime.cpp:581
    frame #9: 0x0000000103f4556e
    frame #10: 0x0000000101dbe3d3 QtQml_debug`QV4::ExecutionContext::simpleCall(this=0x000000010c36f750, scope=0x00007fff5fbfb668, callData=0x000000010c36f6e8, function=0x0000000102e86680) at qv4context.cpp:302
    frame #11: 0x0000000101df0fd5 QtQml_debug`QV4::ScriptFunction::call(that=0x000000010c36f740, scope=0x00007fff5fbfb668, callData=0x000000010c36f6e8) at qv4functionobject.cpp:409
    frame #12: 0x0000000101cf6a21 QtQml_debug`QV4::Object::call(this=0x000000010c36f740, scope=0x00007fff5fbfb668, d=0x000000010c36f6e8) const at qv4object_p.h:445
    frame #13: 0x0000000101f0f4f6 QtQml_debug`QV4::Runtime::method_callProperty(engine=0x00000001030a0200, nameIndex=8, callData=0x000000010c36f6e8) at qv4runtime.cpp:1104
    frame #14: 0x0000000103f4450e
    frame #15: 0x0000000101dbe3d3 QtQml_debug`QV4::ExecutionContext::simpleCall(this=0x000000010c36f6b8, scope=0x00007fff5fbfb8c8, callData=0x000000010c36f650, function=0x0000000102e2a7e0) at qv4context.cpp:302
    frame #16: 0x0000000101df0fd5 QtQml_debug`QV4::ScriptFunction::call(that=0x000000010c36f6a8, scope=0x00007fff5fbfb8c8, callData=0x000000010c36f650) at qv4functionobject.cpp:409
    frame #17: 0x0000000101cf6a21 QtQml_debug`QV4::Object::call(this=0x000000010c36f6a8, scope=0x00007fff5fbfb8c8, d=0x000000010c36f650) const at qv4object_p.h:445
    frame #18: 0x0000000101f0f7e3 QtQml_debug`QV4::Runtime::method_callElement(engine=0x00000001030a0200, index=0x000000010c0ec610, callData=0x000000010c36f650) at qv4runtime.cpp:1141
    frame #19: 0x0000000109726457
    frame #20: 0x0000000101dbdf46 QtQml_debug`QV4::ExecutionContext::call(this=0x000000010c36f5c0, scope=0x00007fff5fbfbbc8, callData=0x000000010c36f558, function=0x0000000102f731f0, f=0x000000010c36f5b8) at qv4context.cpp:274
    frame #21: 0x0000000101df1020 QtQml_debug`QV4::ScriptFunction::call(that=0x000000010c36f5b0, scope=0x00007fff5fbfbbc8, callData=0x000000010c36f558) at qv4functionobject.cpp:411
    frame #22: 0x0000000101cf6a21 QtQml_debug`QV4::Object::call(this=0x000000010c36f5b0, scope=0x00007fff5fbfbbc8, d=0x000000010c36f558) const at qv4object_p.h:445
    frame #23: 0x0000000101f0ef99 QtQml_debug`QV4::Runtime::method_callActivationProperty(engine=0x00000001030a0200, nameIndex=111, callData=0x000000010c36f558) at qv4runtime.cpp:1052
    frame #24: 0x0000000109726bbc
    frame #25: 0x0000000101dbe3d3 QtQml_debug`QV4::ExecutionContext::simpleCall(this=0x000000010c36f510, scope=0x00007fff5fbfbec8, callData=0x000000010c36f4a8, function=0x0000000102f73400) at qv4context.cpp:302
    frame #26: 0x0000000101df0fd5 QtQml_debug`QV4::ScriptFunction::call(that=0x000000010c36f500, scope=0x00007fff5fbfbec8, callData=0x000000010c36f4a8) at qv4functionobject.cpp:409
    frame #27: 0x0000000101cf6a21 QtQml_debug`QV4::Object::call(this=0x000000010c36f500, scope=0x00007fff5fbfbec8, d=0x000000010c36f4a8) const at qv4object_p.h:445
    frame #28: 0x0000000101f0ef99 QtQml_debug`QV4::Runtime::method_callActivationProperty(engine=0x00000001030a0200, nameIndex=113, callData=0x000000010c36f4a8) at qv4runtime.cpp:1052
    frame #29: 0x000000010972ae6f
    frame #30: 0x0000000101dbdf46 QtQml_debug`QV4::ExecutionContext::call(this=0x000000010c36f410, scope=0x00007fff5fbfc1c8, callData=0x000000010c36f3a8, function=0x0000000102f73460, f=0x000000010c36f408) at qv4context.cpp:274
    frame #31: 0x0000000101df1020 QtQml_debug`QV4::ScriptFunction::call(that=0x000000010c36f400, scope=0x00007fff5fbfc1c8, callData=0x000000010c36f3a8) at qv4functionobject.cpp:411
    frame #32: 0x0000000101cf6a21 QtQml_debug`QV4::Object::call(this=0x000000010c36f400, scope=0x00007fff5fbfc1c8, d=0x000000010c36f3a8) const at qv4object_p.h:445
    frame #33: 0x0000000101f0ef99 QtQml_debug`QV4::Runtime::method_callActivationProperty(engine=0x00000001030a0200, nameIndex=115, callData=0x000000010c36f3a8) at qv4runtime.cpp:1052
    frame #34: 0x000000010972c1f1
    frame #35: 0x0000000101dbe3d3 QtQml_debug`QV4::ExecutionContext::simpleCall(this=0x0000000103f98088, scope=0x00007fff5fbfc5b0, callData=0x000000010c36f328, function=0x0000000102f73c20) at qv4context.cpp:302
    frame #36: 0x0000000101ff9df2 QtQml_debug`QQmlJavaScriptExpression::evaluate(this=0x0000000102e86870, callData=0x000000010c36f328, isUndefined=0x0000000000000000, scope=0x00007fff5fbfc5b0) at qqmljavascriptexpression.cpp:223
    frame #37: 0x0000000101f5ec4f QtQml_debug`QQmlBoundSignalExpression::evaluate(this=0x0000000102e86870, a=0x0000000000000000) at qqmlboundsignal.cpp:223
    frame #38: 0x0000000101f5f3de QtQml_debug`QQmlBoundSignal_callback(e=0x0000000102e864d0, a=0x0000000000000000) at qqmlboundsignal.cpp:355
    frame #39: 0x0000000101fd1e5d QtQml_debug`QQmlNotifier::emitNotify(endpoint=0x0000000000000000, a=0x0000000000000000) at qqmlnotifier.cpp:106
    frame #40: 0x0000000101f2ff23 QtQml_debug`QQmlData::signalEmitted((null)=0x0000000102e867c0, object=0x0000000102ec2920, index=3, a=0x0000000000000000) at qqmlengine.cpp:856
    frame #41: 0x00000001004ce8be QtCore_debug`QMetaObject::activate(sender=0x0000000102ec2920, signalOffset=3, local_signal_index=0, argv=0x0000000000000000) at qobject.cpp:3644
    frame #42: 0x00000001004ce7fd QtCore_debug`QMetaObject::activate(sender=0x0000000102ec2920, m=0x00000001020f8aa0, local_signal_index=0, argv=0x0000000000000000) at qobject.cpp:3629
    frame #43: 0x0000000102096b82 QtQml_debug`QQmlComponentAttached::completed(this=0x0000000102ec2920) at moc_qqmlcomponentattached_p.cpp:138
    frame #44: 0x000000010201f2e8 QtQml_debug`QQmlObjectCreator::finalize(this=0x0000000102ea78f0, interrupt=0x00007fff5fbfe588) at qqmlobjectcreator.cpp:1339
    frame #45: 0x0000000101f5196c QtQml_debug`QQmlComponentPrivate::complete(enginePriv=0x0000000102e2a270, state=0x0000000102e29d40) at qqmlcomponent.cpp:920
    frame #46: 0x0000000101f4f95b QtQml_debug`QQmlComponentPrivate::completeCreate(this=0x0000000102e29ca0) at qqmlcomponent.cpp:956
    frame #47: 0x0000000101f51a32 QtQml_debug`QQmlComponent::completeCreate(this=0x0000000102eab840) at qqmlcomponent.cpp:949
    frame #48: 0x0000000101f50e46 QtQml_debug`QQmlComponent::create(this=0x0000000102eab840, context=0x0000000102f97ca0) at qqmlcomponent.cpp:775
    frame #49: 0x0000000102900789 QtQuick_debug`QQuickView::continueExecute(this=0x00007fff5fbfebb8) at qquickview.cpp:471
    frame #50: 0x00000001029004a4 QtQuick_debug`QQuickViewPrivate::execute(this=0x0000000102eab530) at qquickview.cpp:107
    frame #51: 0x0000000102900bf0 QtQuick_debug`QQuickView::setSource(this=0x00007fff5fbfebb8, url=0x00007fff5fbfeaf0) at qquickview.cpp:236
    frame #52: 0x00000001000a20c0 QtQuickTest_debug`quick_test_main(argc=1, argv=0x00007fff5fbfefc8, name="all", sourceDir=".") at quicktest.cpp:515
    frame #53: 0x0000000100004ff5 singletonbug`main(argc=1, argv=0x00007fff5fbfefc8) at singletonbug.cpp:11
    frame #54: 0x00007fffa99f7235 libdyld.dylib`start + 1
    frame #55: 0x00007fffa99f7235 libdyld.dylib`start + 1