Executinhg build.sh fails to locate `build.ninja`

Hi,

vala, ninja and meson are installed, but build.sh seems to not be able to locate all necessary files:

╰─>$ ./build.sh
ninja: error: loading 'build.ninja': No such file or directory
cp: cannot stat 'src/com.gitlab.baschdel.dragonstone': No such file or directory

Is this an issue on my end or something that could be tweaked in the build process?

Best, Georg