我无法在MacOS上安装jupyterlab-manager扩展名。当我从JupyterLab运行时：
! jupyter labextension install @jupyter-widgets/jupyterlab-manager
我获得：
```An error occured.
ValueError: Please install nodejs 5+ and npm before continuing installation. nodejs may be installed using conda or directly from the nodejs website.
See the log file for details: /var/folders/0m/4t1p5b792753jm8j1l7ygx580000gn/T/jupyterlab-debug-xn6qmoh9.log```
尽管我已经正确安装了Nodejs v12（操作系统认可）和npm。
有人知道如何解决这个问题吗？
非常感谢！