LambdaA to invoke LambdaB - circular reference when trying to include LambdaB function name in LambdaA environment

gistfile1.txt

    const s3PutLambdaRole = new iam.Role(this, "S3PutLambdaRole", {
      assumedBy: new iam.ServicePrincipal("lambda.amazonaws.com")
      // managedPolicyArns:
    });

    bucket.grantRead(s3PutLambdaRole);

    const s3EventLambda = new lambda.Function(this, "s3PutHandler", {
      runtime: lambda.Runtime.NodeJS810,
      code: lambda.Code.directory("resources"),
      role: s3PutLambdaRole,
      handler: "cache.processEvent",
      memorySize: 1000,
      timeout: 60,
      environment: {
        BUCKET: bucket.bucketName // provides bucket name to runtime
      }
    });

    s3EventLambda.addEventSource(
      new S3EventSource(bucket, {
        events: [s3.EventType.ObjectCreated]
      })
    );

    //////////////// Fanout Lambda
    const dynamoLambdaRole = new iam.Role(this, "DynamoLambdaRole", {
      assumedBy: new iam.ServicePrincipal("lambda.amazonaws.com")
    });
    dynamoLambdaRole.addToPolicy(
      new iam.PolicyStatement()
        .addAction("dynamoDB:*")
        .addResource(table.tableArn)
    );

    const fanoutLambda = new lambda.Function(this, "fanoutWorker", {
      runtime: lambda.Runtime.NodeJS810,
      code: lambda.Code.directory("chunk_processor"),
      role: dynamoLambdaRole,
      handler: "index.processChunk",
      memorySize: 1000,
      timeout: 60,
      environment: {
        table: table.tableName
      }
    });

    // allow s3PutLambda to call fanout lambda
    s3PutLambdaRole.addToPolicy(
      new iam.PolicyStatement()
        .addAction("lambda:InvokeFunction")
        .addResource(fanoutLambda.functionArn)
    );

    // pass fanoutLambda name to s3Event
    s3EventLambda.addEnvironment(
      "fanoutLambda", fanoutLambda.functionName // circular ref here
    );