index.js

module.exports =
  (pluginOptions = {}) =>
  (nextConfig = {}) => {
    return Object.assign({}, nextConfig, {
      webpack(config, options) {
        const { include } = pluginOptions;

        if (!include) {
          throw new Error('You need to define an include folder to make this plugin work');
        }

        if (!options.defaultLoaders) {
          throw new Error(
            'This plugin is not compatible with Next.js versions below 5.0.0 https://err.sh/next-plugins/upgrade',
          );
        }

        config.module.rules.push({
          test: /\.(svg)$/,
          include,
          loader: 'svg-react-loader',
        });

        if (typeof nextConfig.webpack === 'function') {
          return nextConfig.webpack(config, options);
        }

        return config;
      },
    });
  };