[vala/0.46] gnutls: Fix "use of possibly unassigned parameter" warnings

[Rico Tzschichholz <ricotz src gnome org>]

commit 2cd9d7994ffe3d57d58cfce5b1e82eb55da30bbd
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sat Oct 5 10:35:20 2019 +0200

    gnutls: Fix "use of possibly unassigned parameter" warnings

 vapi/gnutls.vapi | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/vapi/gnutls.vapi b/vapi/gnutls.vapi
index b7bd2817b..a7299af33 100644
--- a/vapi/gnutls.vapi
+++ b/vapi/gnutls.vapi
@@ -402,8 +402,11 @@ namespace GnuTLS
                {
                        Priority result;
                        var ret = init (out result, priority, out err_pos);
-                       if (&err != null)
+                       if (&err != null) {
                                err = (ErrorCode) ret;
+                       } else {
+                               err = 0;
+                       }
                        return result;
                }
        }