Need help building asprite

Hello everyone!
I am trying to build Aseprite on Ubuntu 18.04 LTS, following this tutorial: https://alexgonzalezc.dev/posts/how-to-build-aseprite-from-source.html

At the step where I run “ninja -C out/Release skia”, I receive the following error:

ninja: error: ‘…/…/third_party/externals/expat/lib/xmlparse.c’, needed by ‘obj/third_party/externals/expat/lib/expat.xmlparse.o’, missing and no known rule to make it

Anyone out there who can assist?