Warning: React.createElement: type is invalid -- expected a string

[nakamn]

Trying to get react-checkbox-tree(1.6.0) to play nicely, but getting the following error in the browser console:

React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports

index.js

import React from 'react';
import CheckboxTree from 'react-checkbox-tree';
import 'react-checkbox-tree/lib/react-checkbox-tree.css';

const nodes = [{
  value: 'mars',
  label: 'Mars',
  children: [
    { value: 'phobos', label: 'Phobos' },
    { value: 'deimos', label: 'Deimos' },
  ],
}];

class Widget extends React.Component {
  state = {
    checked: [],
    expanded: [],
  };

  render() {
    return (
      <CheckboxTree
        nodes={nodes}
        checked={this.state.checked}
        expanded={this.state.expanded}
        onCheck={checked => this.setState({ checked })}
        onExpand={expanded => this.setState({ expanded })}
      />
    );
  }
}

export default Widget;

[Jake Zatecky]

Interesting. There does not seem to be any issue in the code you have written.

Have you used a previous version and had any errors?

I suspect that the bundler you are using (e.g., Webpack) may not be resolving the library correctly. Can you point to a live example with this error or modify this reference point?

[kutsyk-neocles]

Hey,

Any update guys? I'm using webpack too and have this problem.
But no issues with any other libs.

Should I change my webpack or in what way can I make it work?

Here is mine webpack:

const path = require("path");
const fs = require("fs");
const CopyWebpackPlugin = require("copy-webpack-plugin");

const entries = {};
const srcDir = path.join(__dirname, "src");
fs.readdirSync(srcDir)
  .filter(dir => fs.statSync(path.join(srcDir, dir)).isDirectory())
  .forEach(dir => (entries[dir] = "./" + path.join("src", dir, dir)));

module.exports = {
  target: "web",
  entry: entries,
  node: {
    fs: "empty"
  },
  output: {
    filename: "[name]/[name].js",
  },
  devtool: "inline-source-map",
  context: __dirname,
  devServer: {
    https: true,
    port: 3000,
    publicPath: "/dist/"
  },
  resolve: {
    extensions: [".ts", ".tsx", ".js"],
    alias: {
      "azure-devops-extension-sdk": path.resolve(
        "node_modules/azure-devops-extension-sdk"
      )
    }
  },
  stats: {
    warnings: true,
    errorDetails: true
  },
  module: {
    rules: [
      {
        test: /\.tsx?$/,
        use: "ts-loader"
      },
      {
        test: /\.scss$/,
        use: [
          "style-loader",
          "css-loader",
          "azure-devops-ui/buildScripts/css-variables-loader",
          "sass-loader"
        ]
      },
      {
        test: /\.css$/,
        use: ["style-loader", "css-loader"]
      },
      {
        test: /\.woff$/,
        use: [
          {
            loader: "base64-inline-loader"
          }
        ]
      },
      {
        test: /\.html$/,
        use: "file-loader"
      }
    ]
  },
  plugins: [new CopyWebpackPlugin([{ from: "**/*.html", context: "src" }])]
};

[Jake Zatecky]

Hello @kutsyk-neocles, is it possible for you to create a simplified repo that replicates this error?

[Marius]

I'm having same issue (react 16.13) + webpack (4.4.1)

[Jake Zatecky]

Please re-open if this issue persists with the latest version and include a repo/codepen that replicates it.