--install-missing flag is working in the opposite way: if set, then the value is False (missing packages are not installed), and the opposite if not set (value is True)
Possible solution: change default value on line to False
If the library is supposed to install missing packages, but all packages are installed, then the function for installing packages would be called with an empty list. That would result failer in for DNF command on this line
Two things here:
--install-missingflag is working in the opposite way: if set, then the value isFalse(missing packages are not installed), and the opposite if not set (value isTrue)False