docs: function mutateJsonFile(targetPath, source, mutator) {
    if (!mutator) {
      mutator = source;
      source = null;
    }
    let sourceConfig = source;
    try {
      // console.log('targetPath', targetPath);
  
      let targetConfig = readJson(targetPath);
  
      // console.log('source', source);
      if (typeof source === 'string') {
        sourceConfig = readJson(source);
      }
      // console.log('sourceConfig', targetPath, sourceConfig)
      sourceConfig = sourceConfig ? sourceConfig : targetConfig;
  
      let newConfig = mutator(targetConfig, sourceConfig);
  
      writeJson(targetPath, newConfig, {spaces: 2});
  
    } catch (e) {
      log.error('Error: operating on aurelia.json. Reverting to previous version ;{}', e);
      writeJson(targetPath, sourceConfig, {spaces: 2});
    }
  }