Getting run.sh no such file

[25thbamofthetower]

/opt/bootstrap: line 3: /var/task/path/to/run.sh

I'm trying to set up FastAPI, but getting that error. I used the run.sh file in the example, and have this in my CDK:

const lambda = new Function(..., {
    code: Code.fromAsset(...),
    handler: 'run.sh',
    layer: [LayerVersion.fromLayerVersionArn(...)],
    environments: {
      AWS_LAMBDA_EXEC_WRAPPER: '/opt/bootstrap',
      AWS_LWA_PORT: '443'
   }
})

Does anyone know what I'm missing? Thanks!