[evolution] Avoid crash when validating a new filter rule

[Milan Crha <mcrha src gnome org>]

commit d192749ad28acde84b3b9d888ec53c7866a60996
Author: Milan Crha <mcrha redhat com>
Date:   Tue Feb 17 17:10:50 2015 +0100

    Avoid crash when validating a new filter rule
    
    A simple filter rule based on a Subject and a Move of the message
    to a certain folder caused a crash of the application on save.

 e-util/e-filter-input.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/e-util/e-filter-input.c b/e-util/e-filter-input.c
index 1bfa029..8fa31d0 100644
--- a/e-util/e-filter-input.c
+++ b/e-util/e-filter-input.c
@@ -79,7 +79,7 @@ filter_input_validate (EFilterElement *element,
 
        g_warn_if_fail (alert == NULL || *alert == NULL);
 
-       if (input->values && !strcmp (input->type, "regex")) {
+       if (input->values && input->type && !strcmp (input->type, "regex")) {
                const gchar *pattern;
                regex_t regexpat;
                gint regerr;