CICD- given key not present in the dictionary

Question

trigger:
  branches:
    include:
      - main  

pool:
  name: vibe  # Use the 'vibe' agent pool
  demands:
    - agent.name -equals Kibe_test  

variables:
  # Assuming credentials are handled as pipeline variables or service connections
  System.Debug: true
  TEST_VAR: "HelloWorld"

jobs:
  - job: Build
    timeoutInMinutes: 120  # Timeout for the entire job (equivalent to Jenkins' pipeline timeout)
    steps:
      - task: Checkout@1
        displayName: 'Clone Repository to Agent'

      - script: |
          echo "Add other tasks to build, test, and deploy your project."
          echo "See https://mehul/yaml"
          echo "TEST_VAR: $(TEST_VAR)"
        displayName: 'Echo TEST_VAR'

Error - when agent runs the pipeline it's throw error "given key not present in the dictionary"