patch 8.2.5013: after text formatting cursor may be in an invalid position

Problem:    After text formatting the cursor may be in an invalid position.
Solution:   Correct the cursor position after formatting.

src/textformat.c

@@ -870,6 +870,9 @@ op_format(
     {
 	curwin->w_cursor = saved_cursor;
 	saved_cursor.lnum = 0;
+
+	// formatting may have made the cursor position invalid
+	check_cursor();
     }
 
     if (oap->is_VIsual)