patch 8.2.2977: crash when using a null function reference

Problem:    Crash when using a null function reference. (Naohiro Ono)
Solution:   Check for an invalid function name. (closes #8367)
diff --git a/src/version.c b/src/version.c
index 08f06cf..19a159d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2977,
+/**/
     2976,
 /**/
     2975,