eslint is complaining about line 12

.eslintrc.json

{
    "env": {
        "browser": true,
        "node": true,
        "commonjs": true,
        "es6": true,
        "mocha": true
    },
    "extends": [
        "eslint:recommended",
        "plugin:react/recommended"
    ],
    "parserOptions": {
        "parser": "babel-eslint",
        "ecmaVersion": 2018,
        "ecmaFeatures": {
            "jsx": true,
            "experimentalObjectRestSpread": true
        },
        "sourceType": "module"
    },
    "plugins": [
        "react"
    ],
    "rules": {
        "indent": [
            "error",
            "tab"
        ],
        "arrow-body-style": ["error", "as-needed"],
        "linebreak-style": [
            "error",
            "unix"
        ],
        "quotes": [
            "error",
            "double"
        ],
        "semi": [
            "error",
            "always"
        ],
        "no-unused-vars": [
            "error",
            {
                "varsIgnorePattern": "should"
            }
        ]
    }
}

CreateNewMainTopic.js

import React, {Component} from "react";
import axios from "axios";
import $ from "jquery";

class CreateNewMainTopic extends Component{
	constructor(props){
		super(props);
		this.onSubmit = this.onSubmit.bind(this);
		this.inputTitle = React.createRef();
		this.inputPercentage = React.createRef();
	}
	static defaultProps = {
		title: "MainTopic title",
		percentage_concluded: "0"
	};

	onSubmit(e){
		e.preventDefault();
		axios.post("http://localhost:8080/api/maintopic",
			{
				title: this.inputTitle.current.value,
                percentage_concluded: this.inputPercentage.current.value
			})
			.then(
				$.ajax({
					url: "/api/all",
					dataType: "json",
					success: function (dados) {
						this.setState({matter: dados})
					}.bind(this)
				})
			);
	};

	render() {
		const {title, percentage_concluded} = this.props;
		return(
			<div className="card mb-3">
				<div className="card-header">Add a New Main Topic</div>
				<div className="card-body">
					<form onSubmit={this.onSubmit}>
						<div className="form-group">
							<label htmlFor="title">Title</label>
							<input type="text" className="form-control " name="title" placeholder="Title" defaultValue={title} ref={this.inputTitle}/>
						</div>
						<div className="form-group">
							<label htmlFor="percentage_concluded">Percentage Concluded</label>
							<input type="number" className="form-control " name="percentage_concluded" placeholder="Percentage Concluded" defaultValue={percentage_concluded} ref={this.inputPercentage}/>
						</div>
						<input type="submit" className="btn btn-light"/>
					</form>
				</div>
			</div>
		);
	}
}

export default CreateNewMainTopic;