refactored the cache loader

- adjusted formatting to make it easier to read
- added the key prefix from config
- made everything failsafe since users don't have that configured by default

application/controllers/Api.php

@@ -1255,7 +1255,11 @@ class API extends CI_Controller {
 		}
 
 		// Load cache driver
-		$this->load->driver('cache', ['adapter' => $this->config->item('cache_adapter'), 'backup' => $this->config->item('cache_backup')]);
+		$this->load->driver('cache', [
+			'adapter' => $this->config->item('cache_adapter') ?? 'file', 
+			'backup' => $this->config->item('cache_backup')	 ?? 'file',
+			'key_prefix' => $this->config->item('cache_key_prefix') ?? ''
+		]);
 
 		// Create cache key
 		$cache_key = "wp_stats_{$station_id}";