Is there an issue with the posted source code file? I’ve downloaded it twice and many of the files are filled with null content (Notepad++). For example
Chapter One: activity_main.xml:
NULNULNULNULNULNULNULNULNULNULNULNUL
In a browser, the error is: error on line 9 at column 1: Document is empty
Kotlin files (MainActivity.kt, Chapter One, for example) don’t even have the header. They are just completely filled with NUL