Handled the case of missing containers in XPath

[Mayureshpawar29]

Description

• When scraping multiple URLs, different pages may have different HTML structures. Previously, if a container XPath didn't exist on one page, the entire pipeline would fail. This made it impossible to process mixed content where some pages have the container and others don't.

• Test pipeline

tasks:
  - name: read_urls
    type: file
    path: test/pipelines/urls.txt
    
  - name: split
    type: split
    
  - name: prepare_request
    type: jq
    path: |
      {
        endpoint: .,
        method: "GET"
      }
      
  - name: fetch_html
    type: http
    
  - name: extract_data
    type: xpath
    ignore_missing: true  # <-- Test this flag
    container: "//*[@id='wrap']/div/div/div/div[3]/div[2]/div/div"
    fields:
      title: "./div"
      
  - name: output
    type: echo
    only_data: true

Test URLs (test/pipelines/urls.txt):

"https://www.example.com/"
"https://publicwww.com/"

• Pipeline continues when ignore_missing: true and container missing

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation and I have updated the documentation accordingly.
• I have added tests to cover my changes.
• I have checked downstream dependencies (e.g. ExternalTaskSensors) by searching for DAG name elsewhere in the repo