[evolution-ews] Add parameter check into ews_get_error_code()

[Milan Crha <mcrha src gnome org>]

commit bc8cf909af6876bdd17bbea6ee5667cd741d36d4
Author: Milan Crha <mcrha redhat com>
Date:   Tue May 26 10:07:52 2020 +0200

    Add parameter check into ews_get_error_code()
    
    This may eventually fix:
    https://retrace.fedoraproject.org/faf/reports/2928715/

 src/server/ews-errors.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/server/ews-errors.c b/src/server/ews-errors.c
index 35a05a38..53c3cda7 100644
--- a/src/server/ews-errors.c
+++ b/src/server/ews-errors.c
@@ -331,6 +331,9 @@ ews_get_error_code (const gchar *str)
        gint error_code = EWS_CONNECTION_ERROR_UNKNOWN;
        gpointer data;
 
+       if (!str)
+               return error_code;
+
        g_once (&setup_error_once, setup_error_map, NULL);
 
        data = g_hash_table_lookup (ews_error_hash, (gconstpointer) str);