AWS Lambda Layer in AWS Serverless App Repository does not list nodejs 12 as a compatible layer
This issue indicates that nodejs 12 is compatible: #21
If you click on deploy in the serverless app repository page and open up >Template the template tells me only NodeJS 10 is supported. Not having 12 listed results in being unable to select the layer if you are creating a NodeJS 12 lambda function.

Sharing with others suffering the same: I've downloaded the layer as .zip file, and created another version of it, but this time selecting node 12.x as compatible runtime. You should do the same in your Layers section of the Lambda function.
Sharing with others suffering the same: I've downloaded the layer as
.zipfile, and created another version of it, but this time selecting node12.xas compatible runtime. You should do the same in your Layers section of the Lambda function.
Thanks @raelgc ! Very helpful