Here is a more detailed gdb output

terminate called after throwing an instance of 'std::out_of_range'                                                                                               
  what():  basic_string::at: __n (which is 19) >= this->size() (which is 19)                                                                                     

Thread 1 "gwenview" received signal SIGABRT, Aborted.                                                                                                            
0xf7fd5079 in __kernel_vsyscall ()                                                                                                                               
(gdb) bt                                                                                                                                                         
#0  0xf7fd5079 in __kernel_vsyscall ()                                                                                                                           
#1  0xf5d1ea02 in __libc_signal_restore_set (set=0xffffc0cc) at ../sysdeps/unix/sysv/linux/nptl-signals.h:80                                                     
#2  __GI_raise (sig=6) at ../sysdeps/unix/sysv/linux/raise.c:48                                                                                                  
#3  0xf5d1fe91 in __GI_abort () at abort.c:79                                                                                                                    
#4  0xf5f3b97d in ?? () from /usr/lib/i386-linux-gnu/libstdc++.so.6                                                                                              
#5  0xf5f43174 in ?? () from /usr/lib/i386-linux-gnu/libstdc++.so.6                                                                                              
#6  0xf5f431dd in std::terminate() () from /usr/lib/i386-linux-gnu/libstdc++.so.6                                                                                
#7  0xf5f434dc in __cxa_throw () from /usr/lib/i386-linux-gnu/libstdc++.so.6                                                                                     
#8  0xf5f6defa in std::__throw_out_of_range_fmt(char const*, ...) () from /usr/lib/i386-linux-gnu/libstdc++.so.6                                                 
#9  0xf5881da3 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::at (__n=19, this=0xffffc67c)                                  
    at /usr/include/c++/7/bits/basic_string.h:1098                                                                                                               
#10 Exiv2::Internal::printXmpDate (os=..., value=...) at tags.cpp:2774                                                                                           
#11 0xf58c3aff in Exiv2::Xmpdatum::write (this=0xe7016260, os=...) at xmp.cpp:281                                                                                
#12 0xf7d870af in Exiv2::operator<< (md=..., os=...) at /usr/include/exiv2/metadatum.hpp:305                                                                     
#13 Gwenview::ImageMetaInfoModelPrivate::fillExivGroup<Exiv2::XmpData, __gnu_cxx::__normal_iterator<Exiv2::Xmpdatum const*, std::vector<Exiv2::Xmpdatum, std::all
ocator<Exiv2::Xmpdatum> > > > (this=<optimized out>, parent=..., group=<optimized out>, container=...) at ./lib/imagemetainfomodel.cpp:284                       
#14 0xf7d8212f in Gwenview::ImageMetaInfoModel::setExiv2Image (this=<optimized out>, image=<optimized out>) at ./lib/imagemetainfomodel.cpp:454                  
#15 0xf7d2fa54 in Gwenview::Document::setExiv2Image (this=0x56ad70b0, image=...) at ./lib/document/document.cpp:395                                              
#16 0xf7d2e7f0 in Gwenview::AbstractDocumentImpl::setDocumentExiv2Image (this=0x56b73570, image=...) at ./lib/document/abstractdocumentimpl.cpp:82               
#17 0xf7d434b3 in Gwenview::LoadingDocumentImpl::slotMetaInfoLoaded (this=0x56b73570) at ./lib/document/loadingdocumentimpl.cpp:491                              
#18 0xf7debf44 in Gwenview::LoadingDocumentImpl::qt_static_metacall (_o=0x56b73570, _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xffffcb78)                      
    at ./obj-i686-linux-gnu/lib/gwenviewlib_autogen/DV7UALDUNI/moc_loadingdocumentimpl.cpp:85                                                                    
#19 0xf6303c6e in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/i386-linux-gnu/sse2/libQt5Core.so.5
[...]

I hope this helps.