Fix error handling if no PSK found for main mode

src/libcharon/sa/ikev1/tasks/main_mode.c

@@ -799,13 +799,13 @@ static shared_key_t *lookup_shared_key(private_main_mode_t *this)
 		{
 			shared_key = lib->credmgr->get_shared(lib->credmgr, SHARED_IKE,
 												  my_id, other_id);
-		}
+			if (!shared_key)
-		else
 			{
 				DBG1(DBG_IKE, "no shared key found for '%Y'[%H] - '%Y'[%H]",
 					 my_id, me, other_id, other);
 			}
 		}
+	}
 	else
 	{	/* as responder, we try to find a config by IP */
 		enumerator_t *enumerator;
@@ -862,6 +862,10 @@ static bool derive_keys(private_main_mode_t *this, chunk_t nonce_i,
 		case AUTH_XAUTH_INIT_PSK:
 		case AUTH_XAUTH_RESP_PSK:
 			shared_key = lookup_shared_key(this);
+			if (!shared_key)
+			{
+				return FALSE;
+			}
 			break;
 		default:
 			break;