Cant get rid off error TypeError: Cannot read property 'startsWith' of undefined

Serverless Framework
,
1

Hello,
Learning serverless and statemachines. Getting error as in topic: TypeError: Cannot read property ‘startsWith’ of undefined.
Below you can find mu yml definition. Hope someone can help.

service: state-machine

plugins:
  - serverless-python-requirements
  - serverless-iam-roles-per-function
  - serverless-step-functions
  - serverless-pseudo-parameters

custom:
  pythonRequirements:
    dockerizePip: non-linux
    slim: true
    zip: true

provider:
  name: aws
  runtime: python3.8
  region: eu-central-1
  stage: ${opt:stage, 'testing'}
  timeout: 30

  iamRoleStatements:
    - Effect: Allow
      Action:
        - lambda:InvokeFunction
        - lambda:InvokeAsync
      Resource: "*"

package:
  individually: true
  exclude:
    - node_modules/**
    - .git/**
    - .venv/**

functions:
  process-purchase:
    module: state-machine
    memorySize: 128
    stages:
      - testing
      - dev
    handler: ProcessPurchase.process_purchase

  process-refund:
    module: state-machine
    memorySize: 128
    stages:
      - testing
      - dev
    handler: ProcessRefund.process_refund

stepFunctions:
  validate: true
  stateMachines:
    TransactionChoiceMachine:
      name: ChoiceMachineTest-${self:provider.stage}
      dependsOn: CustomIamRole
      definition:
        Comment: "Purchase refund choice"
        StartAt: ProcessTransaction
        States:
          ProcessTransaction:
            Type: Choice
            Choices:
              - Variable: "$.TransactionType"
                StringEquals: "PURCHASE"
                Next: PurchaseState
              - Variable: "$.TransactionType"
                StringEquals: "REFUND"
                Next: RefundState
          PurchaseState:
            Type: Task
            Resource:
              Fn::GetAtt: [process-purchase, Arn]
            End: true
          RefundState:
            Type: Task
            Resourse:
              Fn::GetAtt: [process-refund, Arn]
            End: true
2

Found typo in the code /facepalm, case closed.