How to fix these PHP Warnings with the "Feed JSON" plug-in?

Question

I'm getting the following PHP warnings when using the WordPress plug-in "Feed JSON". Can someone tell me how to fix them?

Warning: Invalid argument supplied for foreach() in /mypath/wp-content/plugins/feed-json/feed-json-template.php on line 39

Warning: Cannot modify header information - headers already sent by (output started at /mypath/wp-content/plugins/feed-json/feed-json-template.php:39) in /mypath/wp-content/plugins/feed-json/feed-json-template.php on line 53

Here is the code used in feed-json-template. Lines 39 and 53 are highlighted with ** around each line.

<?php
/**
 * JSON Feed Template for displaying JSON Posts feed.
 *
 */
$callback = trim(esc_html(get_query_var('callback')));
$charset = get_bloginfo('charset');

if ( have_posts() ) {
    $json = array();
    while ( have_posts() ) {
        the_post();
        $id = (int) $post->ID;

        $single = array(
            'id'        => $id ,
            'title'     => get_the_title() ,
            'permalink' => get_permalink(),
            'content'   => get_the_content(),
            'excerpt'   => get_the_excerpt(),
            'date'      => the_date('Y-m-d H:i:s','','',false) ,
            'author'    => get_the_author() ,
            );

        // thumbnail
        if (has_post_thumbnail($id)) {
            $single["thumbnail"] = preg_replace("/^.*['\"](https?:\/\/[^'\"]*)['\"].*/i","$1",get_the_post_thumbnail($id));
        }

        // category
        $categories = array();
        foreach((get_the_category()) as $category) { 
            $categories[] = $category->cat_name; 
        }
        $single["categories"] = $categories;

        // tag
        $tags = array();
        **foreach((get_the_tags()) as $tag) {** 
            $tags[] = $tag->name; 
        }
        $single["tags"] = $tags;

        $json[] = $single;
    }
    $json = json_encode($json);

    nocache_headers();
    if (!empty($callback)) {
        header("Content-Type: application/x-javascript; charset=$charset");
        echo "$callback($json);";
    } else {
        **header("Content-Type: application/json; charset=$charset");**
        echo "$json";
    }

} else {
    header("HTTP/1.0 404 Not Found");
    wp_die("404 Not Found");
}
?>

Answer 1

Probably get_the_tags() is returning an empty array. Try changing the function to:

$my_tags = get_the_tags();
if ($my_tags){
    foreach($my_tags as $tag) {
        $tags[] = $tag->name; 
    }
}