Random crash in QUtf8::convertFromUnicode - SegFault accessing nextAscii and src

Baloo suddenly crashed, but it looks like a Qt issue. Here's the relevant backtrace - unfortunately a few things are optimized out:

```

#3  0x00007f0ed21861a2 in KCrash::defaultCrashHandler (...)

#4  <signal handler called

#5  QUtf8::convertFromUnicode (in=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/text/qstringconverter.cpp:490
       u = <optimized out>
       res = <optimized out>
       nextAscii = 0x3 <error: Cannot access memory at address 0x3>
       len = <optimized out>
       result = {d = {d = 0x7eceb0005e50, ptr = 0x7eceb0005e60 "", size = 3}, static _empty = 0 '\000'}
       dst = 0x7eceb0005e60 ""
       src = 0x1 <error: Cannot access memory at address 0x1>
       end = <optimized out>
#6  0x00007f0ed1890238 in qt_convert_to_utf8 (str=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/text/qstring.cpp:5666
No locals.
#7  QString::toUtf8_helper (str=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/text/qstring.cpp:5658
No locals.
#8  0x00007f0ed1e3e226 in QString::toUtf8() const & (this=0x7f0ebe5ff338) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/text/qstring.h:619
No locals.
#9  QDBusMarshaller::append (this=this@entry=0x7f0ebe5ff350, arg=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/dbus/qdbusmarshaller.cpp:102
       data = {d = {d = 0x7eceb0005e50, ptr = 0x7eceb0005e60 "", size = 3}, static _empty = 0 '\000'}
       cdata = 0xefb4ac7e2c616a00 <error: Cannot access memory at address 0xefb4ac7e2c616a00>
#10 0x00007f0ed1e4082f in QDBusMarshaller::append (this=0x55b65734e068, arg=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/dbus/qdbusmarshaller.cpp:210
       s = @0x55b65734e050: {d = {d = 0x31, ptr = 0x1 <error: Cannot access memory at address 0x1>, size = 1}, static _empty = 0 u'\000'}
       __for_range = @0x7f0ebe5ff330: {<QListSpecialMethods<QString>> = {<QListSpecialMethodsBase<QString>> = {<No data fields>{color:#000000}}, <No data fields>{color:#000000}}, d = {d = 0x55b65734e040,  
           ptr = 0x55b65734e050, size = 2}}
       __for_begin = <optimized out>
       __for_end = <optimized out>
       sub = {<QDBusArgumentPrivate> = {_vptr.QDBusArgumentPrivate = 0x7f0ed1ed6120 <vtable for QDBusMarshaller+16>, message = 0x0,  
           ref = {<QAtomicInteger<int>> = {<QBasicAtomicInteger<int>> = {_q_value = std::atomic<int> = { 1 }}, <No data fields>{color:#000000}}, <No data fields>{color:#000000}}, capabilities = {i = 1},  
           direction = QDBusArgumentPrivate::Direction::Marshalling{color:#000000}}, iterator = {dummy1 = 0x7f0eb8023300, dummy2 = 0x7f0e01e00000, dummy3 = 3193921900, dummy4 = 32526,  
           dummy5 = -1338954128, dummy6 = 32462, dummy7 = 1, dummy8 = 250, dummy9 = -1207815344, dummy10 = 32526, dummy11 = 4, pad1 = 4, pad2 = 0x100000000, pad3 = 0x7f0ebe5ff57f{color:#000000}},  
         parent = 0x7f0ebe5ff530, ba = 0x0, errorString = {d = {d = 0x0, ptr = 0x0, size = 0}, static _empty = 0 u'\000'}, closeCode = 0 '\000', ok = true, skipSignature = false}
       sub = <optimized out>
       s = <optimized out>
       __for_range = <optimized out>
       __for_begin = <optimized out>
       __for_end = <optimized out>
#11 QDBusMarshaller::appendVariantInternal (this=this@entry=0x7f0ebe5ff530, arg=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/dbus/qdbusmarshaller.cpp:446
       id = {d_ptr = 0x7f0ed1c896a0 <QtPrivate::QMetaTypeInterfaceWrapper<QList<QString> >::metaType>}
       signature = <optimized out>
#12 0x00007f0ed1e77caf in QDBusMessagePrivate::toDBusMessage (message=..., capabilities=..., error=error@entry=0x7f0ebe5ff7f0)
   at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/dbus/qdbusmessage.cpp:178
       argument = @0x7eceb0014610: {d = {static MaxInternalSize = 24, data = {data = "@\3404W\266U\000\000P\3404W\266U\000\000\002\000\000\000\000\000\000", shared = 0x55b65734e040,  
             _forAlignment = 4.6561554504442892e-310}, is_shared = 0, is_null = 0, packedType = 34925406463400}}
       __for_range = <optimized out>
       __for_begin = <optimized out>
       __for_end = <optimized out>
       msg = 0x7f0eb8023300
       d_ptr = <optimized out>
       marshaller = {<QDBusArgumentPrivate> = {_vptr.QDBusArgumentPrivate = 0x7f0ed1ed6120 <vtable for QDBusMarshaller+16>, message = 0x0,  
           ref = {<QAtomicInteger<int>> = {<QBasicAtomicInteger<int>> = {_q_value = std::atomic<int> = { 1 }}, <No data fields>{color:#000000}}, <No data fields>{color:#000000}}, capabilities = {i = 1},  
           direction = QDBusArgumentPrivate::Direction::Marshalling{color:#000000}}, iterator = {dummy1 = 0x7f0eb8023300, dummy2 = 0x7f0e01e00000, dummy3 = 3193831532, dummy4 = 32526,  
           dummy5 = -1338954128, dummy6 = 32462, dummy7 = 2, dummy8 = 250, dummy9 = -1207815344, dummy10 = 32526, dummy11 = 0, pad1 = 32462, pad2 = 0x7f0ebe5ff5e0,  
           pad3 = 0x7f0ebe5ff57f{color:#000000}}, parent = 0x0, ba = 0x0, errorString = {d = {d = 0x0, ptr = 0x0, size = 0}, static _empty = 0 u'\000'}, closeCode = 0 '\000', ok = true,  
         skipSignature = false}
#13 0x00007f0ed1e529a1 in QDBusConnectionPrivate::send (this=0x7f0eb8001450, message=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/corelib/global/qflags.h:34
       error = {code = QDBusError::NoError, msg = {d = {d = 0x0, ptr = 0x0, size = 0}, static _empty = 0 u'\000'}, nm = {d = {d = 0x0, ptr = 0x0, size = 0}, static _empty = 0 u'\000'},  
         unused = 0x7f0ebe5ff990{color:#000000}}
       msg = <optimized out>
#14 0x00007f0ed1e53077 in QDBusConnectionPrivate::send (this=<optimized out>, message=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/dbus/qdbusintegrator.cpp:1967
       error = <optimized out>
       msg = <optimized out>
       qt_category = <optimized out>
       qt_category = <optimized out>
       qt_category = <optimized out>
#15 0x00007f0ed1e43f5e in QDBusConnection::send (this=<optimized out>, message=...) at /usr/src/debug/qt6-qtbase-6.7.2-6.fc40.x86_64/src/dbus/qdbusconnection.cpp:316
No locals.
#16 0x000055b655c6bfdf in (anonymous namespace)::sendChangedSignal (updatedFiles=...) at /usr/src/debug/kf6-baloo-6.7.0-1.fc40.x86_64/src/file/filecontentindexer.cpp:27
       message = {d_ptr = 0x7eceb02f4840{color:#000000}}
       message = <optimized out>

(...)

```