How to set custom plugin throttling

[gschoenberger]

Unfortunately I cannot pass custom throttling settings to lighthouse.
This is my plugin config:

    "plugins": [
              {
                  "name": "lighthouse",
                  "label": "desktop",
                  "report": true,
                  "config": {
                       "extends": "lighthouse:default",
                       "settings": {
                               "emulatedFormFactor": "desktop",
                               "throttling" : {
                                       "rttMs": "40",
                                       "throughputKbps": "10240"
                               }
                        }
                   }
              }
      ]

According to the generated report the settings are set correctly:

But the performance score only shows an error:

When I am removing the "throttling" section the report is generated correctly, with correct performance score.

Any hints on how to set throttling or get more error reporting, why performance cannot be calculated?

THX, Georg