Generated alter table script when column is not null - possible bug

Hello,
when i want to modify column size (eg. VARCHAR2(5) to VARCHAR2(10)), wrong alter table script is generated if column is already NOT NULL.

In editor type table name, describe table using F4, click “alter selected table” icon, change size of any column that is already NOT NULL.

Generated script looks like

ALTER TABLE TABLE_OWNER.TABLE_NAME
MODIFY(COLUMN_NAME VARCHAR2(10 BYTE) NOT NULL)
/

Running this script leads to ORA-01442 error (column to be modified to NOT NULL is already NOT NULL)

I presume that this is a bug. Toad version is 12.5.0.99