tunneling socket could not be established, cause=connect ECONNREFUSED 127.0.0.1:56281 npm ERR! network This is most likely not a problem with npm itself npm ERR! network and is related to network

tunneling socket could not be established, cause=connect ECONNREFUSED 127.0.0.1:56281
npm ERR! network This is most likely not a problem with npm itself
npm ERR! network and is related to network connectivity.
npm ERR! network In most cases you are behind a proxy or have bad network settings.

错误原因：我开了代理。

解决方案：npm config set proxy null