[evolution] em-format: Guard entry point to em_format_set_mode with g_return_if_fail

[Rob Bradford <rbradford src gnome org>]

commit 2b6e5cce1912d6d7bb7f69b7cae29ccb0c8a7161
Author: Rob Bradford <rob linux intel com>
Date:   Mon Aug 2 15:05:32 2010 +0100

    em-format: Guard entry point to em_format_set_mode with g_return_if_fail

 em-format/em-format.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/em-format/em-format.c b/em-format/em-format.c
index c318655..a323c56 100644
--- a/em-format/em-format.c
+++ b/em-format/em-format.c
@@ -859,6 +859,8 @@ em_format_redraw (EMFormat *emf)
 void
 em_format_set_mode(EMFormat *emf, em_format_mode_t type)
 {
+	g_return_if_fail (EM_IS_FORMAT (emf));
+
 	if (emf->mode == type)
 		return;