function isSafeToCreateProjectIn()

in packages/create-react-app/createReactApp.js [906:976]
63 lines of code
6 McCabe index (conditional complexity)

function isSafeToCreateProjectIn(root, name) {
  const validFiles = [
    '.DS_Store',
    '.git',
    '.gitattributes',
    '.gitignore',
    '.gitlab-ci.yml',
    '.hg',
    '.hgcheck',
    '.hgignore',
    '.idea',
    '.npmignore',
    '.travis.yml',
    'docs',
    'LICENSE',
    'README.md',
    'mkdocs.yml',
    'Thumbs.db',
  ];
  // These files should be allowed to remain on a failed install, but then
  // silently removed during the next create.
  const errorLogFilePatterns = [
    'npm-debug.log',
    'yarn-error.log',
    'yarn-debug.log',
  ];
  const isErrorLog = file => {
    return errorLogFilePatterns.some(pattern => file.startsWith(pattern));
  };

  const conflicts = fs
    .readdirSync(root)
    .filter(file => !validFiles.includes(file))
    // IntelliJ IDEA creates module files before CRA is launched
    .filter(file => !/\.iml$/.test(file))
    // Don't treat log files from previous installation as conflicts
    .filter(file => !isErrorLog(file));

  if (conflicts.length > 0) {
    console.log(
      `The directory ${chalk.green(name)} contains files that could conflict:`
    );
    console.log();
    for (const file of conflicts) {
      try {
        const stats = fs.lstatSync(path.join(root, file));
        if (stats.isDirectory()) {
          console.log(`  ${chalk.blue(`${file}/`)}`);
        } else {
          console.log(`  ${file}`);
        }
      } catch (e) {
        console.log(`  ${file}`);
      }
    }
    console.log();
    console.log(
      'Either try using a new directory name, or remove the files listed above.'
    );

    return false;
  }

  // Remove any log files from a previous installation.
  fs.readdirSync(root).forEach(file => {
    if (isErrorLog(file)) {
      fs.removeSync(path.join(root, file));
    }
  });
  return true;
}