Prestashop problem

test my module using the official docker image of prestashop 1.7.
When I click on save button no validation message is displayed, i should add a validation/error message when i save the form like screenshot 2.







This i got from prestashop

You can use the official docker image of prestashop from here : http://hub.docker.com/r/prestashop/prestashop/
You should have to do the verification on your side to display validation message.
Please fix this issue and submit your module.

:confused:

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My question is where to go in which folder in which file on which line need to add code and what code needed to be add.Please help
i have been working with my friend 30 days on this can someno help .