Beitragsbilder erscheinen nicht, stattdessen Fehlermeldung getimagesize

<?php
/**
* @package HowlThemes
*/
?>
[FONT=inherit]<article id="post-<?php the_ID(); ?>" <?php post_class(); ?> itemscope="itemscope" itemtype="http://schema.org/BlogPosting" itemprop="blogPost">
<header class="entry-header">
<?php the_title( sprintf( '<h2 class="entry-title" itemprop="headline"><a href="%s" rel="bookmark">', esc_url( get_permalink() ) ), '</a></h2>' ); ?>[/FONT]
[FONT=inherit]<?php if ( 'post' == get_post_type() ) : ?>
<div class="entry-meta">
<div class="postdcp"><?php drag_themes_posted_on(); ?></div>
<?php showstarrating();?>
</div><!-- .entry-meta -->
<?php endif; ?>
</header><!-- .entry-header -->[/FONT]
[FONT=inherit]<div class="entry-content">
<div class="thumbnail-container" itemprop="image">
<?php 
if ( get_the_post_thumbnail() != '' ) {
echo '<a href="'; the_permalink(); echo '" class="thumbnail-wrapper">';
$source_image_url = wp_get_attachment_url( get_post_thumbnail_id($post->ID, 'thumbnail') );
$imginfo = getimagesize($source_image_url);
if($imginfo[0] >= 250 && $imginfo[1] >= 200){
$resizedImage = aq_resize($source_image_url, 250, 200, true);
}
else{
$resizedImage = $source_image_url;
}
echo '<img src="';
echo $resizedImage;
echo '" alt="';the_title();
echo '" />';
echo '</a>';
} elseif(catch_that_image()){
$source_image_url = catch_that_image();
$imginfo = getimagesize($source_image_url);
if($imginfo[0] >= 250 && $imginfo[1] >= 200){
$resizedImage = aq_resize($source_image_url, 250, 200, true);
}
else{
$resizedImage = $source_image_url;
}
echo '<a href="'; the_permalink(); echo '" class="thumbnail-wrapper">';
echo '<img src="';
echo $resizedImage;
echo '" alt="';the_title();
echo '" />';
echo '</a>';
}
else{
echo '<a href="'; the_permalink(); echo '" class="thumbnail-wrapper">';
echo '<img src="';
echo esc_url( get_template_directory_uri() );
echo '/img/thumbnail.jpg" alt="';the_title();
echo '" />';
echo '</a>';
}
?>
</div>
<div class="entry-summary" itemprop="text">
<?php the_excerpt(); ?></div>
</div><!-- .entry-content -->[/FONT]
[FONT=inherit]<footer class="entry-footer">
<div class="read-more-button"><a href="<?php the_permalink(); ?>"><?php _e( 'Read More', 'aqueduct-pro' ); ?> <i class="fa fa-long-arrow-right"></i></a></div>
</footer><!-- .entry-footer -->
</article><!-- #post-## -->[/FONT]

<?php/** * The template for displaying all single posts. * * @package HowlThemes */
get_header(); ?>
<div class="main-outer container">  <div id="primary" class="content-area">    <main id="main" class="site-main" role="main" itemprop="mainContentOfPage" itemscope="itemscope" itemtype="http://schema.org/Blog">
    <?php while ( have_posts() ) : the_post(); ?>
      <?php get_template_part( 'content', 'single' ); ?>
            <div class="post-navss">      <?php the_post_navigation(); ?>            </div>
<div class="howl-sharing-buttons"><?php sharingbuttons(); ?></div>
<div class="relatedposts"><?php//for use in the loop, list 5 post titles related to first tag on current post$tags = wp_get_post_tags($post->ID);if ($tags) {echo '<p>'. __( "Related Posts", "aqueduct-pro" ) . '</p>';$first_tag = $tags[0]->term_id;$args=array('tag__in' => array($first_tag),'post__not_in' => array($post->ID),'posts_per_page'=>3,'ignore_sticky_posts'=>1);$my_query = new WP_Query($args);if( $my_query->have_posts() ) {  $randnum =1;while ($my_query->have_posts()) : $my_query->the_post();?><div class="related-posts rpost<?php echo $randnum; ?>"><?php if ( get_the_post_thumbnail() != '' ) {   $source_image_url = wp_get_attachment_url( get_post_thumbnail_id($post->ID, 'thumbnail') );  $resizedImage = aq_resize($source_image_url, 220, 170, true);  echo '<a href="'; the_permalink(); echo '" class="thumbnail-wrapper">';    echo '<img src="';   echo $resizedImage;   echo '" alt="';the_title();   echo '" />';    echo '</a>';    }     elseif(catch_that_image()){   $source_image_url = catch_that_image();   $resizedImage = aq_resize($source_image_url, 220, 170, true);   echo '<a href="'; the_permalink(); echo '" class="thumbnail-wrapper">';   echo '<img src="';   echo $resizedImage;   echo '" alt="';the_title();   echo '" />';   echo '</a>';    }     else{   echo '<a href="'; the_permalink(); echo '" class="thumbnail-wrapper">';    echo '<img src="';    echo esc_url( get_template_directory_uri() );    echo '/img/simplethumbnail.jpg" alt="';the_title();    echo '" />';    echo '</a>';}  ?>    <h2><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></h2></div><?php$randnum++;endwhile;}wp_reset_query();}?></div>
<div class="ads-container-cmnt">  <?php echo stripslashes(get_option('dt_custom_ads_abovecmt')) ?></div>
      <?php        // If comments are open or we have at least one comment, load up the comment template        if ( comments_open() || get_comments_number() ) :          comments_template();        endif;      ?>
    <?php endwhile; // end of the loop. ?>
    </main><!-- #main -->  </div><!-- #primary -->
<?php get_sidebar(); ?></div><?php get_footer(); ?>