Fix error management

htdocs/admin/tools/export.php

@@ -189,6 +189,7 @@ if ($what == 'mysql')
         $ok=0;
         dol_syslog("Run command ".$fullcommandcrypted);
         $handlein = popen($fullcommandclear, 'r');
+        if ($handlein) {
 	        while (!feof($handlein))
 	        {
 	            $read = fgets($handlein);
@@ -197,7 +198,7 @@ if ($what == 'mysql')
 	            elseif (preg_match('/'.preg_quote('SET SQL_NOTES=@OLD_SQL_NOTES').'/i',$read)) $ok=1;
 	        }
 	        pclose($handlein);
-
+        }
         if ($compression == 'none') fclose($handle);
         if ($compression == 'gz')   gzclose($handle);
         if ($compression == 'bz')   bzclose($handle);