Silencing errors from certain plugins and themes in Query Monitor

Hide PHP notices from a plugin named “foo”:

add_filter( 'qm/collect/php_error_levels', function( array $levels ) {
 $levels['plugin']['foo'] = ( E_ALL & ~E_NOTICE );
 return $levels;
} );

Only report warnings from your child theme, and completely silence errors from its parent theme

add_filter( 'qm/collect/php_error_levels', function( array $levels ) {
 $levels['theme']['stylesheet'] = ( E_WARNING & E_USER_WARNING );
 $levels['theme']['template']   = ( 0 );
 return $levels;
} );

To silence deprecated errors from WordPress core:

add_filter( 'qm/collect/php_error_levels', function( $levels ) {
 $levels['core']['core'] = ( E_ALL & ~E_DEPRECATED );
 return $levels;
} );

Disable Error

define( 'QM_DISABLE_ERROR_HANDLER', true );