TypeError: can't access property "inscrever", this.props.categories is undefined

Eu estou em dúvida que está me dando esse type error. Segue o código abaixo:

 constructor(props) {
    super(props);
    this.title = "";
    this.text = "";
    this.category = "Sem categoria";
    this.state = {categories: []}
  }

  componentDidMount(){
    this.props.categories.inscrever(this._newCategories.bind(this));
  }

  _newCategories(categories){
    this.setState({...this.state, categories});
  }

  _mudarCategoria(evento){
    evento.stopPropagation();
    this.category = evento.target.value;
  }


  _handleMudarTitulo(evento) {
    evento.stopPropagation();
    this.title = evento.target.value;
  }

 constructor(){
    super();
    this.state = {notes: []}
  }

componentDidMount(){
  this.props.notes.inscrever(this._newNotes.bind(this));
}

_newNotes(notes){
  this.setState({...this.state, notes})
}

  render() {
    return (
      <ul className="lista-notas">
        {this.state.notes.map((nota, index) => {
          return (
            <li className="lista-notas_item" key={index}>
              <NoteCard
                indice ={index}
                apagarNota={this.props.apagarNota}
                title={nota.title}
                text={nota.text}
                category = {nota.category}
              />
            </li>
          );
        })}
      </ul>
    );
  }
}

export default NoteList;