Illegal offset type while creating new record in laravel

I am trying to create new record using seeder.

This is the code i wrote on seeder file:

RoleUser::create(['role_id'=>$roleId[0],'user_id'=>$user->id]);
PermissionRole::create(['permission_id'=>1,'role_id'=>$roleId[0]]);

This is the error i am getting

[ErrorException] Illegal offset type 

RoleUser model is used for role_user table

Schema::create('role_user', function (Blueprint $table) {
        $table->integer('role_id')->unsigned();
        $table->integer('user_id')->unsigned();
        $table->primary(['role_id','user_id']);
    });

PermissionRole model is used for permission_role table

Schema::create('permission_role', function (Blueprint $table) {
        $table->integer('permission_id')->unsigned();
        $table->integer('role_id')->unsigned();
        $table->primary(['permission_id','role_id']);
    });

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