Ignore the `.dotrun.json` file if it is corrupted

During the startup this script loads a file called `.dotrun.json` which is used as a state of the project. Currently of the `json.loads` fails dotrun is unusable and the user will have to manually delete the file: `.dotrun.json`.

### Proposed fix

Add a try/catch in case of `ValueError`, delete the file `.dotrun.json` as it is corrupted.

Start at the startup path that loads `.dotrun.json` and inspect the `json.loads` call described in the issue. Verify the corrupted-file case is handled by removing `.dotrun.json` and allowing dotrun to start again; the payload does not name a test file.

Written by the indexing model from the issue text.