How can I fix the undefined array errors on my wordpress website?

My wordpress site indicates an undefined array on line 1001 & 1004 of plugin.php:

**1001**  if ( is_object( $callback[0] ) ) {
        // Object class calling.
        return spl_object_hash( $callback[0] ) . $callback[1];
**1004**  } elseif ( is_string( $callback[0] ) ) {
        // Static calling.
        return $callback[0] . '::' . $callback[1];
    }

My wordpress child theme’s functions.php code is this:

<?php
add_action( `wp_enqueue_scripts`, `theme_enqueue_styles`); 
function theme_enqueue_styles() {
wp_enqueue_style( `parent-style`, get_template_directory_uri() . `/style.css`);
}

How can i modify it? The errors only appeared when I activated my child theme, so I figured that’s where the problem is. My child theme only has a css file and the functions.php…

I tried to deactivate all plugins since the error said it came from plugin.php at first, it didn’t work

I tried modifying the code of plugin.php to this

if (is_string($callback[0]) || is_object($callback[0])) {
// Static or object calling.
return $callback[0] . '::' . $callback[1];
} else {
// Object class calling.
return spl_object_hash($callback[0]) . $callback[1];
}

made everything worse

I don’t know much php so I would rather ask. Thank you for your help