Thanks. The thing is, I do not have any blank lines or spaces in my wp-config.php file. I misinterpreted the warning to mean the problem was in the wp-includes/pluggable.php, so I removed an extra line there. I finally found the FAQ and I don’t have any extra space in line 1.
Should I put the extra line back in pluggable.php?
<?php
/**
* The base configurations of the WordPress.
*
* This file has the following configurations: MySQL settings, Table Prefix,
* Secret Keys, WordPress Language, and ABSPATH. You can find more information by
* visiting {@link https://codex.www.ads-software.com/Editing_wp-config.php Editing
* wp-config.php} Codex page. You can get the MySQL settings from your web host.
*
* This file is used by the wp-config.php creation script during the
* installation. You don’t have to use the web site, you can just copy this file
* to “wp-config.php” and fill in the values.
*
* @package WordPress
*/
// ** MySQL settings – You can get this info from your web host ** //
/** The name of the database for WordPress */