A user inadvertently created an invalid host definition in the strategies.yaml. When configuring the scheme section of a host the user added the port element as an array field. The parser allowed this but at runtime, the next hop lookup failed to get the proper port number which caused a runtime assertion failure.

Incorrect YAML:

    protocol:
        - scheme: http
        - port:  80

Correct YAML:

    protocol:
        - scheme: http
          port: 80

This is also correct but maybe more clear:

   protocol:
      -
        scheme: http
        port:  80
      -
        scheme: https
        port:  443

The YAML parser should catch and report the error.