salix/services/item/common/models/item-niche.js

const UserError = require('vn-loopback/common/helpers').UserError;

module.exports = Self => {
    Self.rewriteDbError(function(err) {
        if (err.code === 'ER_DUP_ENTRY')
            return new UserError(`The warehouse can't be repeated`);
        return err;
    });
};