This function will display author name, bio and Gravtar when author has no posts.

display_author_info.php

<?php // do not include this line in functions.php 

add_filter( 'the_author', function( $name ) {
	$author = get_user_by( 'slug', get_query_var( 'author_name' ) );
	return $author->display_name;
} );

add_filter( 'get_the_author_description', function( $value, $user_id, $original_user_id ) {
	$author = get_user_by( 'slug', get_query_var( 'author_name' ) );
	return $author->description;
}, 10, 3 );

add_filter( 'get_the_author_user_email', function( $value, $user_id, $original_user_id ) {
	$author = get_user_by( 'slug', get_query_var( 'author_name' ) );
	return $author->user_email;
}, 10, 3 );