generateCommands should detect bad formats in YAML file

Some of the elements of the YAML file can be a bit tricky to get right, especially the bootstrap and fiberProfiles blocks, with their group syntax, e.g.:

    bootstrap:
      group:
        -
          flatId: visit=45742
          arcId: visit=45744

In such cases, omitting the extra group structure results in generateCommands silently skipping the operation.

Please produce errors when the YAML file format will result in incorrect operation, or YAML elements are misnamed or in the wrong place.