问题描述：
跟着教程配置kibana的开发环境时，运行命令yarn kbn bootstrap时报如下错误：

Installing dependencies in [@kbn/es]:

[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
error An unexpected error occurred: "Reduce of empty array with no initial value".
info If you think this is a bug, please open a bug report with the information provided in "/home/cfischer/kibana/packages/kbn-es/yarn-error.log".
info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.

[bootstrap] failed:

Error: Command failed: yarn install --non-interactive --mutex file
    at makeError (/home/cfischer/kibana/packages/kbn-pm/dist/index.js:44877:9)
    at Promise.all.then.arr (/home/cfischer/kibana/packages/kbn-pm/dist/index.js:44982:16)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:188:7)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

解决方案：
这是由于yarn的版本是1.7造成的，安装1.6版本的yarn完美解决了。

版本：
- elasticsearch:6.3.0
- kibana:6.3.0
- node:8.11.3
- yarn:1.6

本人最近在开发kibana插件，包括但不限于：汉化kibana，二次开发kibana，有意一起研究的小伙伴可以加我QQ：820327571（备注kibana）