fix: throw InvalidDataException if Cli tool cannot open input file

And adjust the related unit test testConvertDefaultFormats so that
it handles the PHP warning that is emitted by fopen.

The Cli code catches InvalidDataException and exits with status 2,
which is what was always expected by the unit test code. So this
should preserve the real behavior.

The test changes are necessary because PHPunit11 now exposes the
PHP warning coming from fopen. So we catch and expect that in an
error handler in the test.