Write to fix the problem you need to change a few lines. I have also uploaded a new zip file with the fix and a few more changes to the code.
1. Delete the assets/cache folder.
2. Make sure the script can write to the following folders, (666 should be fine, 777 for sure)
assets
|- admin
|- css
|- js
|- public
|- css
|- js
|- shared
|- css
|- js
3. Replace the code on line 50
Replace this:
$file_path = $this->CI->config->item('asset_cache_path') . $this->CI->config->item('asset_cache_prefix') . $main . "." . $type;
With this:
$file_path = $this->CI->config->item($main . '_assets') . $type . "/" . $this->CI->config->item('asset_cache_file') . "." . $type;
4. In the asset_linker config file change the following
Replace this (around line 81):
/*
|--------------------------------------------------------------------------
| Cache File Prefix
|--------------------------------------------------------------------------
| String to prepend to asset cache files.
*/
$config['asset_cache_prefix'] = "asset_cache_";
/*
|--------------------------------------------------------------------------
| Cache Path
|--------------------------------------------------------------------------
| Path to where cache files are stored. Should be relative to base_url()
| and be able to be seen by public. IE don't set it to the CI cache folder.
| String should end with a trailing slash
*/
$config['asset_cache_path'] = $config['assets_dir'] . 'cache/';
With this:
/*
|--------------------------------------------------------------------------
| Asset Cache File
|--------------------------------------------------------------------------
| File name you want the cache files to be called, please don't include extensions
*/
$config['asset_cache_file'] = "cache";
That will change the class so the cache files will be saved locally to the original style sheets so relative paths will still work.
As I said above I will upload a new version of the zip file with the changes in and a few extra ones I have discovered upon looking over it.