A developer file that resolves the broken images coming from post thumbnail, and redux framework. Besides that, it will also provide some functions that will log or print the output only if wp debug is set to true

developer.php

<?php

add_filter( 'wp_get_attachment_image_src', 'fillup_broken_image_src',10,2);
function fillup_broken_image_src($image, $attachment_id){
	$path = get_attached_file($attachment_id);
	if(!file_exists($path)){
		$w = isset($image[1])?$image[1]:1348;
		$h = isset($image[2])?$image[2]:600;
		$image[0] = 'http://placehold.it/'.$w.'x'.$h;
	}
	return $image;
}

add_filter( 'redux/options/ev_intranet/global_variable', 'fillup_broken_image_option' );
function fillup_broken_image_option($data){
	$site_url = rtrim(site_url(), '/');
	$abspath = rtrim(ABSPATH, '/');

	foreach($data as &$opt){
		if(is_array($opt)){
			if(isset($opt['thumbnail'])){
				$file = str_replace($site_url,$abspath, $opt['url']);
				if(!file_exists($file)){
					$opt['url'] = 'http://placehold.it/'.$opt['width'].'x'.$opt['height'];
					$opt['thumbnail'] = 'http://placehold.it/'.$opt['width'].'x'.$opt['height'];
				}
			}	
		}
	}

	return $data;
}


add_filter('post_thumbnail_html','fillup_broken_image_html',10,5);
function fillup_broken_image_html($html, $post_id, $thumb_id, $size,$attr){
	return $html;
}

function ev_dump( $obj,$type=false ){
	if(!defined('WP_DEBUG') || WP_DEBUG != true ){
		return;
	}

	echo '<pre>';

	if($type){
		var_dump($obj);
	}else{
		print_r($obj);
	}

	echo '<pre>';
}


function ev_log($id, $obj, $append=false ){
	if(!defined('WP_DEBUG') || WP_DEBUG != true ){
		return;
	}

	if($append){
		file_put_contents(__DIR__.'/log-'.$id.'.txt', print_r($obj,true), FILE_APPEND );
	}else{
		file_put_contents(__DIR__.'/log-'.$id.'.txt', print_r($obj,true) );
	}
}