Disabling Author Page only for subscribers

Oddly, perhaps, there is no get_user_role function, so not surprising that the earlier answer produced an error.

As per my discussion with Rodney Hawk, I still wonder about the point of this exercise – or what security function this operation serves that wouldn’t be better served by other methods – but, if the preferred objective is to redirect everyone from the author profile page if the author is a “subscriber,” then you might use something like the following:

//for authors template (author.php or variant)
$curauth = (get_query_var('author_name')) ? get_user_by('slug', get_query_var('author_name')) : get_userdata(get_query_var('author')) ;

$author_roles = $curauth->roles ;

if ( in_array( 'subscriber', $author_roles ) ) {
    //probably would want something a little different, but good enough for example
    wp_redirect( 'http://redirect-here.com', 404 ) ;
    //always follow wp_redirect with exit...
    exit ;
}

Note: The $curauth code used above seems to come directly from the Codex. Given the specifics of this case (only for author.php template, only for subscribers), you might be able to write the first lines more simply as follows:

$author_roles = get_user_by('slug', get_query_var('author_name') )->roles ;

Note 2: Haven’t tested the redirection part.