PHP notices on frontend and admin

Frontend:

Notice: Trying to access array offset on value of type bool in C:\Users\helga\Local Sites\sandbox\app\public\wp-content\plugins\wpstream\wpstream.php on line 89

Issue appears to be from calling $share_img[0] when $share_img does not return a value.

I would probably consider updating to something like:

add_action('wp_head', 'wpestate_add_custom_meta_to_header');

function wpestate_add_custom_meta_to_header(){
    global $post;

    if ( is_singular('product') || is_singular('wpstream_product') ) {
        $share_img      =   get_the_post_thumbnail_url( $post, 'full' ); ?>

        <meta property='og:title' content="<?php print esc_html(get_the_title($post->ID)); ?>"/>
        <meta property="og:image" content="<?php print esc_url($share_img); ?>"/>
        <meta property="og:image:secure_url" content="<?php print esc_url($share_img); ?>" />
        <meta property="og:description"  content=" <?php print wp_strip_all_tags( $post->post_content);?>" />
    <?php }

}

Admin:

Notice: Undefined index: default in C:\Users\helga\Local Sites\sandbox\app\public\wp-content\plugins\wpstream\admin\class-wpstream-admin.php on line 852

`

and lastly, I noticed that the wpstream_hide_buy_now_subscription_mode function has a variable called $subscription_model = esc_html( get_option('wpstream_global_sub',true)) ; and this is returning 1 even when the plugin is newly installed and has no options saved. So the admin shows “global subscriptions” as off, but the front-end behaves as if it’s true.