Hello,
when I choose an empty DB folder during installation, the installer complains that it is not empty.
I took a look at the sources and maybe there is an error.
https://github.com/atcurtis/mariadb/blob/master/win/packaging/ca/CustomAction.cpp#L181
Line 181 checks the filename for . or ..
wcscmp returns 0 if the strings are equal (which is interpreted as "false").
This means the if statement is true, if the name is not equal . or not equal ..
This expression is always true becaue every name is not equal . or not equal ..
The operator should be && instead of ||

Regards,
Thomas