more clear error messages

public_html/classes/redirect.admin.class.php

@@ -132,10 +132,10 @@ class redirectadmin extends redirect {
         $aAliases=$this->_getAliases();
         foreach($aAliases as $sAlias=>$sConfig){
             if(isset($aReturn[$sAlias])){
-                $aErrors[]="Alias $sAlias was set already - ".print_r($aReturn[$sAlias]);
+                $aErrors[]="alias.json: Alias [$sAlias] was set already - ".print_r($aReturn[$sAlias], 1);
             } else {
                 if(!isset($aReturn[$sConfig])){
-                    $aErrors[]="Alias $sAlias points to a non existing host $sConfig";
+                    $aErrors[]="alias.json: [$sAlias] points to a non existing host [$sConfig] - a file redirects_$sConfig.yml does not exist.";
                 } else {
                     $aReturn[$sConfig]['aliases'][]=$sAlias;
                     $aReturn[$sAlias]=array(