patch 9.0.1320: checking the type of a null object causes a crash

Problem:    Checking the type of a null object causes a crash.
Solution:   Don't try to get the class of a null object. (closes #12005)
            Handle error from calling a user function better.
diff --git a/src/version.c b/src/version.c
index d6cee20..20df490 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1320,
+/**/
     1319,
 /**/
     1318,