FwLiteWeb creating new sense has entryId "" (empty string), which .NET refuses to parse as a GUID

[rmunn]

Describe the bug
Creating a new sense in an example FwLite project ends up with:

Error: System.Text.Json.JsonException: The JSON value could not be converted to System.Guid. Path: $.senses[0].entryId | LineNumber: 0 | BytePositionInLine: 196.

The JSON in question includes Senses[0] as { id: "00000000-0000-0000-0000-df85dbc25d08", entryId: "", definition: {…}, … } - note entryId being an empty string.

To Reproduce
Steps to reproduce the behavior:

1. Run task fw-lite-web
2. Create new example project
3. Create new sense in first entry
4. Edit definition field, tab out
5. See error

Expected behavior
A missing entryId would be serialized as null rather than an empty string, or the C# backend code would handle the empty string as a special case in deserializing GUIDs and replace it with either null (for a nullable GUID property) or Guid.Empty (for a non-nullable GUID property).

[hahn-kev]

@myieye this looks like it's caused by code in defaultSense (and probably example) in lib/utls.ts we also have some empty id stuff which doesn't look like it's being used anymore, but I don't remember what that was doing. In this case it would make sense to make an empty id constant and use that to solve this bug, but we are calling something else an empty id already.

[hahn-kev]

strike that, this will be closed by #1359