Crash when combining an empty texture

[jeremyshannon]

Minetest version

Minetest 5.9.0-dev-debug-f596c36f4

Irrlicht device

No response

Operating system and version

Devuan Daedalus (eq to Debian Bookworm)

CPU model

No response

GPU model

No response

Active renderer

No response

Summary

Just tracked down a crash in Exile that my team discovered when running MT 590dev, a crash which gave this fairly unhelpful output:
/usr/include/c++/12/string_view:239: constexpr const std::basic_string_view<_CharT, _Traits>::value_type& std::basic_string_view<_CharT, _Traits>::operator[](size_type) const [with _CharT = char; _Traits = std::char_traits<char>; const_reference = const char&; size_type = long unsigned int]: Assertion '__pos < this->_M_len' failed.

A bit of gdb work and it turns out we had some code doing the very dumb thing you see here:
[combine:128x64:0,0=:32,32=cloth_upper_underwear_default.png:0,32=cloth_lower_underwear_default.png
where 0,0=: is an empty texture. I've fixed that now, but there may be other mods out there that will trip this in the future , and it'd probably be polite if the crash output was clearer about what went wrong.

Steps to reproduce

Attempt to run Exile v0.3.16 with current git, or just add a borked "[combine" modifier to whatever object or node you feel like.

[SmallJoker]

02a893d