Add rows in empty table

[6ecuk]

@438561537
Instead compare table===undefined, need compare table===null
https://github.com/casbin/casbin-dashboard/blob/0fbe9c4bb2de5b9383e9feccaa471d8bae5c1c8e/web/src/EnforcerTable.js#L42

[Xiaoyang-Gu]

Maybe we can delete these code? (〃'▽'〃)
https://github.com/casbin/casbin-dashboard/blob/0fbe9c4bb2de5b9383e9feccaa471d8bae5c1c8e/web/src/AdapterTable.js#L38
Because when we start to add a new row, the table has already been a null table " [] ".

[6ecuk]

Well, in practice a table is null i don't know why

[6ecuk]

@438561537 hi, you investigate this case ?

[Xiaoyang-Gu]

@6ecuk Actually, I am working for a new UI frame recently. In the new frame, when I add/edit an model/adapter/enforcer, it will route to another page(not to use addrow() method in the home page).
When I finish the optimization job, I will uploading it after reviewing.
Thank you for your attention!