Follower.php

<?php
//... se omiten los namespaces por brevedad
class CreateFollowersTable extends Migration
{
    
    public function up()
    {
        Schema::create('followers', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('follower_id')->unsigned();
            $table->foreign('follower_id')->references('id')->on('users')->onUpdate('cascade')->onDelete('cascade');
            $table->integer('user_id')->unsigned();
            $table->foreign('user_id')->references('id')->on('users')->onUpdate('cascade')->onDelete('cascade');
            $table->timestamps();
        });
    }
    //... Se omite el metodo down por brevedad
}