[balsa] Do not remove invalid array element

[Peter Bloomfield <PeterB src gnome org>]

commit d489926ffe29e4d048a65b2ef60c576882fce4b1
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Thu Oct 14 21:44:04 2010 -0400

    Do not remove invalid array element

 ChangeLog               |    5 +++++
 libbalsa/mailbox_imap.c |   12 ++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 7c3acef..f871d57 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2010-10-14  Peter Bloomfield
+
+	* libbalsa/mailbox_imap.c (imap_expunge_cb): do not remove
+	invalid array element.
+
 2010-09-26  Peter Bloomfield
 
 	Use separate mutexes for mailbox locking and checking mail
diff --git a/libbalsa/mailbox_imap.c b/libbalsa/mailbox_imap.c
index 84fddf8..6cce6cc 100644
--- a/libbalsa/mailbox_imap.c
+++ b/libbalsa/mailbox_imap.c
@@ -909,7 +909,6 @@ imap_expunge_cb(ImapMboxHandle *handle, unsigned seqno,
 {
     ImapMessage *imsg;
     guint i;
-    gchar *msgid;
 
     LibBalsaMailbox *mailbox = LIBBALSA_MAILBOX(mimap);
     struct message_info *msg_info;
@@ -938,9 +937,14 @@ imap_expunge_cb(ImapMboxHandle *handle, unsigned seqno,
             g_object_unref(msg_info->message);
         g_array_remove_index(mimap->messages_info, seqno-1);
     }
-    msgid = g_ptr_array_index(mimap->msgids, seqno-1);
-    if(msgid) g_free(msgid);
-    g_ptr_array_remove_index(mimap->msgids, seqno-1);
+
+    if (seqno <= mimap->msgids->len) {
+        gchar *msgid;
+
+        msgid = g_ptr_array_index(mimap->msgids, seqno - 1);
+        g_free(msgid);
+        g_ptr_array_remove_index(mimap->msgids, seqno - 1);
+    }
 
     for (i = seqno - 1; i < mimap->messages_info->len; i++) {
 	struct message_info *msg_info =