Added output in case endpoint fails or SELECT query results can't be parsed.

classes/Endpoint.php

@@ -33,10 +33,23 @@ class Endpoint{
         curl_setopt($c, CURLOPT_HTTPHEADER, $context);
         curl_setopt($c, CURLOPT_RETURNTRANSFER, true);
         $aux = curl_exec($c); // execute the curl command 
+        if($conf['debug']){
+          if($aux == false){
+          	trigger_error("Error executing SPARQL query: ".curl_error($c), E_USER_ERROR);
+          	echo("Error executing SPARQL query: ".curl_error($c));
+          }
+        }
         curl_close($c);
         $this->params['output'] = $auxoutput;
         if(preg_match("/select/i", $q)){
           $r = json_decode($aux, true);
+          if($conf['debug']){
+          	if($r == false){
+          	  trigger_error("Warning: Results from a SELECT sparql query couldn't get parsed", E_USER_WARNING);
+          	  echo("Warning: Results from a SELECT sparql query couldn't get parsed");
+          	}
+          }
+        }
           return $r;
         }
         if(preg_match("/describe/i", $q)){