code: function runBuild(cwd /*: string */) /*: Promise<string> */ {
    return new Promise((resolve, reject) => {
      exec(bsb, {maxBuffer: Infinity, cwd}, (err, stdout, stderr) => {
        const output = `${stdout.toString()}\n${stderr.toString()}`
        if (err) {
          reject(output)
        } else {
          resolve(output)
        }
      })
    })
  }
docs: Runs `bsb` async