patch 8.2.4120: block insert goes over the end of the line

Problem:    Block insert goes over the end of the line.
Solution:   Handle invalid byte better.  Fix inserting the wrong text.

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4120,
 /**/
     4119,
 /**/