fix: remove unused non-compliant system method inside 'err' reducer

[tim-lai]

Description

• remove use of system.getSystem() inside the err reducer
• assign empty {} to pass to one of the err-transformer methods as temporary solution. Note, system.getSystem() was used to retrieve the jsonSpec, but then not yet implemented.

This PR does NOT resolve a separate issue regarding migration to redux@4 and react-redux@5

Motivation and Context

Swagger Editor render error when using various sample api definitions. Example from swagger-editor unit test:

swagger: '2.0'
securityDefinitions:
  api_key:
    type: apiKey
    name: apikey
    in: query
    scopes:
      asdf: blah blah
paths:
  /:
    get:
      description: asdf
      security:
        - api_key:
            - 'write:pets'

How Has This Been Tested?

swagger-editor visual render without console errors

Note, existing swagger-ui tests do not catch this error

Screenshots (if appropriate):

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.