Cannot parse "serverless.yml": bad indentation of a mapping entry

I am including various resources defined in external files and I also have output variables in the resources section.

resources:
  - ${file(resources/api-gateway-errors.yml)}
  - ${file(resources/dynamodb-table.yml)}
  - ${file(resources/cognito-user-pool.yml)}
  - ${file(resources/cognito-identity-pool.yml)}
  Outputs:
    CampaignStateMachine:
      Value: !Ref CreateCampaignStateFunction
    ProspectStateMachine:
      Value: !Ref ProspectCreateStateFunction

With the above code, I get the following error:

 Cannot parse "serverless.yml": bad indentation of a mapping entry in "/Users/user/serverless/outreachful-api/serverless.yml" (101:3)
  
    98 |   - ${file(resources/dynamodb-tab ...
    99 |   - ${file(resources/cognito-user ...
   100 |   - ${file(resources/cognito-iden ...
   101 |   Outputs:
  ---------^
   102 |     CampaignStateMachine:
   103 |       Value: !Ref CreateCampaignS ...

If I remove all the external files and keep only the Outputs as such, there is no error:

resources:
  Outputs:
    CampaignStateMachine:
      Value: !Ref CreateCampaignStateFunction
    ProspectStateMachine:
      Value: !Ref ProspectCreateStateFunction

How should I fix this bad indentation problem while including resources through external files as well as having the Output variables?

Thanks in advance.

You could do it like this in my example:

##serverless.yml:
functions: ${file(./sls-functions.yml)}
resources: ${file(./sls-resources.yml)}

## sls-resources.yml
Resources: ${file(./sls-dynamodb.yml)}
Outputs: ${file(./sls-export.yml)}

Sunac, Without knowing the contents of those files, that’s not overly helpful. Do you have the contents of those files?