I am currently using XAMPP/Apache with MariaDB on phpmyadmin. I am trying to create a table based on my code using Doctrine and therefore Annotations for validating a form.
First check your mariadb version. Version 10.1 doesn't support JSON datatype and support for version 10.2 is incomplete.
A workaround is to the version in doctrine.yaml file to
server_version: '5.6'
then regenerate the getters and setters with
php bin/console make:entity --regenerate
then generate the migration file with
php bin/console make:migration
this will generate a migration file with datatype set to LONGTEXT.
Afterwards, in the src/Migrations open each file in there and check for any migration file with JSON as datatype and delete all migration with such datatype. Remember, if you don't delete these files, the next command iterates with each file persisting them to database one by one starting with the old one. If such file exist it will trigger the error again.
Lastly, run
php bin/console doctrine:migrations:migrate
which will persist all the migrations to database accordingly.