Sync fails with error: cannot read property 'length' of undefined

[jpwain]

Describe the bug

Fetch data from Sheets works, but the Sync stage fails, returning this error:

Error: cannot read property 'length' of undefined

To Reproduce

Select a frame that contains a child which contains many correctly-name text objects, e.g. #x_type.r, #x_owner.r, run the plugin, choose Fetch & Sync.

Expected behavior

Objects should populate with random values from the sheet.

Additional context

Fetch works: I can preview the data from the sheet... But then sync fails.