Just a reminder that WP_DEBUG_LOG doesn’t work unless WP_DEBUG is also enabled.
(see Debugging in WP - Codex)
Set both of them to true in config/environments/development.php like this:
define('WP_DEBUG', true); define('WP_DEBUG_LOG', true);
And then WP should log to
app/debug.log
https://codex.wordpress.org/Debugging_in_WordPress#WP_DEBUG_LOG