Input node: displays [object Object] when empty input is given.

### Current Behavior

when an empty (string) payload is sent to the Input node, the field is populated with "[object Object]".

### Expected Behavior

When an empty (string or otherwise) payload is sent to the Input node, it should clear the Input field.
If the input msg is not as expected for whatever reason, it should clear the field and generate an error in debug pane.

### Steps To Reproduce

Send empty string to DB2 Input node.

### Environment

- Dashboard version: 1.13.0
- Node-RED version: 4.0.2
- Browser: Opera, Firefox, Vivaldi

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

I am not a FlowFuse team member