Anyone understand why I can't convert an ARN that I exported in one stack to a string that I read from config?

let iamStack = new pulumi.StackReference(config.require("aws-iam-stack"));

let clusterAutomationAccessRoleArn = iamStack.getOutput("clusterAutomationAccessRoleArn");
if (config.get("clusterAutomationAccessRoleArn") != undefined) {
  clusterAutomationAccessRoleArn = config.require("clusterAutomationAccessRoleArn");
}

index.ts(71,3): error TS2322: Type 'string' is not assignable to type 'Output<any>'.

The ARN is exported in another stack like this:

export const clusterAutomationAccessRoleArn = automationRole.arn;