Error installing Jupyterlab in macOS

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On macOS, with SageMath 9.2 installed via Conda, I tried to install Jupyterlab as follows:

(sage) $ sage -i jupyterlab_widgets

However, I get the following error message:

make: *** No rule to make target 'all-toolchain'.  Stop.

The same error appears if I only try

(sage) $ sage -i jupyterlab

How can I avoid this error and complete the install?

Additional information. I am using a MacBook Pro with macOS 10.13.6, and SageMath 9.2 was installed using conda as follows:

$ conda config --add channels conda-forge
$ conda config --set channel_priority strict
$ conda create -n sage sage python=3.8

I can launch SageMath in the Jupyter notebook with no problems using the commands:

$ conda activate sage
(sage) $ sage -n jupyter

Many thanks.