Created attachment 1443059 [details]
Screenshot of the error

Description of problem:
I've installed grub-customizer with dnf install grub-customizer -y, but when i tried to start it via konsole i've get this output:  

*** initializing (w/o specified bootloader type)…
* reading partition info…
/usr/include/c++/8/bits/basic_string.h:1048: std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::reference std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator[](std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::reference = char&; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]: Assertion '__pos <= size()' failed.
Aborted (core dumped)


Version-Release number of selected component (if applicable):
Fedora 28, Kernel: x86_64 Linux 4.16.11-300, bash 4.4.19, grub-customizer-5.0.6-7, KDE 5.46.0 / Plasma 5.12.5

How reproducible:

Steps to Reproduce:
1. Install grub-customizer
2. Try to launch it from terminal

Actual results:

*** initializing (w/o specified bootloader type)…
* reading partition info…
/usr/include/c++/8/bits/basic_string.h:1048: std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::reference std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator[](std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::reference = char&; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]: Assertion '__pos <= size()' failed.
Aborted (core dumped)