patch 8.2.4318: various comment and indent mistakes, returning wrong zero

Problem:    Various comment and indent mistakes, returning wrong zero.
Solution:   Fix the mistakes.  Return NULL instead of FAIL.
diff --git a/src/evalvars.c b/src/evalvars.c
index b343606..994b979 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -3461,7 +3461,8 @@
 	semsg(_(e_illegal_variable_name_str), name);
 	goto failed;
     }
-    is_script_local = ht == get_script_local_ht() || sid != 0 || var_in_autoload;
+    is_script_local = ht == get_script_local_ht() || sid != 0
+							    || var_in_autoload;
 
     if (vim9script
 	    && !is_script_local