Regressed in 6fbf81c.
There is a missing error check on spl_filesystem_file_read_line(), which
means that if the line could not be read (e.g. because we're at the end
of the file), it will not set intern->u.file.current_line, which will
cause a NULL pointer deref later on.
Fix it by adding a check, and reintroducing the silent flag partially to
be able to throw an exception like it did in the past.
Closes GH-13692.
aa34e0acb4