patch 8.2.4041: using unitialized pointer

Problem:    Using unitialized pointer.
Solution:   Store "ht" when variable is in another script.
diff --git a/src/evalvars.c b/src/evalvars.c
index 965b204..3be9993 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2898,7 +2898,11 @@
 		dictitem_T *di = find_var_in_ht(ht, 0, p + 1, no_autoload);
 
 		if (di != NULL)
+		{
+		    if (htp != NULL)
+			*htp = ht;
 		    return di;
+		}
 	    }
 	}
     }