[evolution] external-editor: Fix a memory leak

[Milan Crha <mcrha src gnome org>]

commit 906f639da696acae0ffc8efe96b3964c916f92be
Author: Milan Crha <mcrha redhat com>
Date:   Wed Apr 22 17:41:58 2020 +0200

    external-editor: Fix a memory leak

 src/plugins/external-editor/external-editor.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/plugins/external-editor/external-editor.c b/src/plugins/external-editor/external-editor.c
index cc77b75fc1..fd140b81bd 100644
--- a/src/plugins/external-editor/external-editor.c
+++ b/src/plugins/external-editor/external-editor.c
@@ -380,7 +380,7 @@ external_editor_thread (gpointer user_data)
                g_idle_add (enable_composer_idle, g_object_ref (eed->composer));
                goto finished;
        } else {
-               gchar *buf;
+               gchar *buf = NULL;
 
                if (g_file_get_contents (filename, &buf, NULL, NULL)) {
                        struct ExternalEditorData *eed2;
@@ -397,6 +397,7 @@ external_editor_thread (gpointer user_data)
                                        "%s: Failed to remove file '%s': %s",
                                        G_STRFUNC, filename, g_strerror (errno));
                        g_free (filename);
+                       g_free (buf);
                }
        }