`undefined is not valid JSON` when attempted to restart Device

### Current Behavior

Customer reported issue.

- A Device is failing to start.
- We don't have device agent logs at this time.
- The `NR Logs` tab on the device page has no logs
- Attempting to restart the device via the actions menu gets a 400 error from the api with a response of `undefined is not valid JSON`

That's all we have at the moment.

Going to look at the 400 error to see what could cause that response and work back from there.

### Expected Behavior

_No response_

### Steps To Reproduce

_No response_

### Environment

- FlowFuse version:
- Node.js version:
- npm version:
- Platform/OS:
- Browser:

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate