Segfault in font engine when laying out unexpected characters

Program received signal SIGSEGV, Segmentation fault.
0xb7616151 in QFontEngineMulti::getGlyphBearings (this=0xb3b13380, glyph=620757477, leftBearing=0x0, rightBearing=0xbfffc6e0) at text/qfontengine.cpp:1491
1491        engine(which)->getGlyphBearings(stripped(glyph), leftBearing, rightBearing);
(gdb) bt
#0  0xb7616151 in QFontEngineMulti::getGlyphBearings (this=0xb3b13380, glyph=620757477, leftBearing=0x0, rightBearing=0xbfffc6e0) at text/qfontengine.cpp:1491
#1  0xb7647cd8 in (anonymous namespace)::LineBreakHelper::adjustRightBearing (this=0xbfffc778, glyph=620757477) at text/qtextlayout.cpp:1665
#2  0xb7647d73 in (anonymous namespace)::LineBreakHelper::adjustPreviousRightBearing (this=0xbfffc778) at text/qtextlayout.cpp:1679
#3  0xb76488bc in QTextLine::layout_helper (this=0xbfffccf0, maxGlyphs=2147483647) at text/qtextlayout.cpp:1832
#4  0xb76478e1 in QTextLine::setLineWidth (this=0xbfffccf0, width=500) at text/qtextlayout.cpp:1564
#5  0xb7e2c2ee in QQuickTextPrivate::setLineGeometry (this=0x80e9df8, line=..., lineWidth=500, height=@0xbfffcce8: 252) at items/qquicktext.cpp:1063
#6  0xb7e2ada1 in QQuickTextPrivate::setupTextLayout (this=0x80e9df8, naturalWidth=0xbfffcf18, baseline=0xbfffcf10) at items/qquicktext.cpp:793
#7  0xb7e295fa in QQuickTextPrivate::updateSize (this=0x80e9df8) at items/qquicktext.cpp:449
#8  0xb7e290a5 in QQuickTextPrivate::updateLayout (this=0x80e9df8) at items/qquicktext.cpp:347
#9  0xb7e2d2e8 in QQuickText::setText (this=0x8124938, n=...) at items/qquicktext.cpp:1432
#10 0xb7f4a1de in QQuickText::qt_metacall (this=0x8124938, _c=QMetaObject::WriteProperty, _id=0, _a=0xbfffd804) at .moc/debug-shared/moc_qquicktext_p.cpp:599
#11 0xb6ca907e in QMetaObject::metacall (object=0x8124938, cl=QMetaObject::WriteProperty, idx=42, argv=0xbfffd804) at kernel/qmetaobject.cpp:306
#12 0xb7baf822 in QV4Bindings::run (this=0x811f4a8, instrIndex=1, executedBlocks=@0x81247bc: 1, context=0x8124b98, error=0x8124798, scope=0x8124938, output=0x8124938, storeFlags=..., table=0x0) at qml/v4/qv4bindings.cpp:2187
#13 0xb7ba8241 in QV4Bindings::run (this=0x811f4a8, binding=0x8124790, flags=...) at qml/v4/qv4bindings.cpp:462
#14 0xb7ba7ae7 in QV4Bindings::subscriptionNotify (this=0x811f4a8, id=1) at qml/v4/qv4bindings.cpp:396
#15 0xb7ba7a59 in QV4BindingsSubscription_callback (e=0x8124c14) at qml/v4/qv4bindings.cpp:383
#16 0xb7b38850 in QQmlNotifier::emitNotify (endpoint=0x8124c14, a=0x0) at qml/qqmlnotifier.cpp:83
#17 0xb7a9044a in QQmlData::signalEmitted (object=0x81246b0, index=37, a=0x0) at qml/qqmlengine.cpp:523
#18 0xb6cdd757 in QMetaObject::activate (sender=0x81246b0, methodOffset=37, signalOffset=28, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3298
#19 0xb7a8bc7a in QQmlVMEMetaObject::activate (this=0x81247d8, object=0x81246b0, index=37, args=0x0) at qml/qqmlvmemetaobject.cpp:1222
#20 0xb7a89bce in QQmlVMEMetaObject::metaCall (this=0x81247d8, c=QMetaObject::WriteProperty, _id=44, a=0xbfffe224) at qml/qqmlvmemetaobject.cpp:719
#21 0xb7a6b081 in QAbstractDynamicMetaObject::metaCall (this=0x81247d8, c=QMetaObject::WriteProperty, _id=44, a=0xbfffe224) at ../../../qtbase/include/QtCore/5.0.0/QtCore/private/../../../../../src/corelib/kernel/qobject_p.h:314
#22 0xb6ca9055 in QMetaObject::metacall (object=0x81246b0, cl=QMetaObject::WriteProperty, idx=44, argv=0xbfffe224) at kernel/qmetaobject.cpp:304
#23 0xb7aabafd in QQmlPropertyPrivate::writeBinding (object=0x81246b0, core=..., context=0x8124b98, expression=0x812221c, result=..., isUndefined=false, flags=...) at qml/qqmlproperty.cpp:1515
#24 0xb7beb00e in QV8Bindings::Binding::update (this=0x812221c, flags=...) at qml/v8/qv8bindings.cpp:176
#25 0xb7beb2f3 in QV8Bindings::Binding::expressionChanged (e=0x812221c) at qml/v8/qv8bindings.cpp:214
#26 0xb7b585a4 in QQmlJavaScriptExpressionGuard_callback (e=0xb3b2bf64) at qml/qqmljavascriptexpression.cpp:376
#27 0xb7b38850 in QQmlNotifier::emitNotify (endpoint=0xb3b2bf64, a=0x0) at qml/qqmlnotifier.cpp:83
#28 0xb7a9044a in QQmlData::signalEmitted (object=0xbffff27c, index=5, a=0x0) at qml/qqmlengine.cpp:523
#29 0xb6cdd757 in QMetaObject::activate (sender=0xbffff27c, methodOffset=5, signalOffset=3, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3298
#30 0xb6cdd606 in QMetaObject::activate (sender=0xbffff27c, m=0x805eca0, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3286
#31 0x08057b5b in tst_QQuickText::mainTextChanged (this=0xbffff27c) at tst_qquicktext.moc:172
#32 0x080572bb in tst_QQuickText::textChanges (this=0xbffff27c) at tst_qquicktext.cpp:147
#33 0x080577dc in tst_QQuickText::qt_static_metacall (_o=0xbffff27c, _c=QMetaObject::InvokeMetaMethod, _id=1, _a=0xbfffe8f0) at tst_qquicktext.moc:92
#34 0xb6cac5f3 in QMetaMethod::invoke (this=0xbfffeaa0, object=0xbffff27c, connectionType=Qt::DirectConnection, returnValue=..., val0=..., val1=..., val2=..., val3=..., val4=..., val5=..., val6=..., val7=..., val8=..., val9=...)
    at kernel/qmetaobject.cpp:2085
#35 0xb6cabb2c in QMetaObject::invokeMethod (obj=0xbffff27c, member=0x80b3ad0 "textChanges", type=Qt::DirectConnection, ret=..., val0=..., val1=..., val2=..., val3=..., val4=..., val5=..., val6=..., val7=..., val8=..., val9=...)
    at kernel/qmetaobject.cpp:1408
#36 0xb79f8966 in QMetaObject::invokeMethod (obj=0xbffff27c, member=0x80b3ad0 "textChanges", type=Qt::DirectConnection, val0=..., val1=..., val2=..., val3=..., val4=..., val5=..., val6=..., val7=..., val8=..., val9=...)
    at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs.h:398
#37 0xb79f45a1 in QTest::qInvokeTestMethodDataEntry (slot=0x80b3ad0 "textChanges") at qtestcase.cpp:1631
#38 0xb79f4da3 in QTest::qInvokeTestMethod (slotName=0x80b3f48 "textChanges()", data=0x0) at qtestcase.cpp:1748
#39 0xb79f560a in QTest::qInvokeTestMethods (testObject=0xbffff27c) at qtestcase.cpp:1902
#40 0xb79f5d82 in QTest::qExec (testObject=0xbffff27c, argc=1, argv=0xbffff354) at qtestcase.cpp:2121
#41 0x08057bd4 in main (argc=1, argv=0xbffff354) at tst_qquicktext.cpp:183