node-mysql2: Concurrent call to mysql breaks after some interaction

I have created an singleton connection to use the same connection_id() so the rest app can make use of TEMPORARY TABLES. After some concurrent calls, the connection is broken with this error:

node_modules/mysql2/lib/connection.js:127
connection.threadId = handshakeCommand.handshake.connectionId;
TypeError: Cannot read property 'connectionId' of null
at ClientHandshake.<anonymous>

He is the code

import { Me } from '../shared/Me';
import * as knex from 'knex';

export class BucketDb {

    private static _connection: { [sessionId: string]: knex } = {};

    public static connect(connectionData) {

        if (!this._connection || (this._connection && !this._connection[Me.profile().sessionId])) {
            this._connection[Me.profile().sessionId] = knex({
                client: 'mysql2',
                connection: connectionData,
                pool: {
                    min: 0, max: 1
                }
            });
        }

        // this._connection[Me.profile().sessionId].raw('select connection_id()').then((r) => {
        //     console.log(Me.profile().sessionId, r[0][0]);
        // });

        return this._connection[Me.profile().sessionId];

    }

}