fix(protocol-designer): set form field value if 1 option, add newLocation error

[ncdiehl11]

Overview

In DropdownStepFormField, if the length of options passed in changes to 1, we need to set the form field value for this component to the single value

Closes RQA-3955

Test Plan and Hands on Testing

• import or create a protocol that will provide 1 single location for moving labware (example)

• verify that the single option is selected, and saving the step form is not blocked

Screen.Recording.2025-02-11.at.9.04.56.AM.mov

Changelog

• add useEffect to select the single option of a DropDownStepFormField if options's length === 1

Review requests

see test plan

Risk assessment

low

[jerader]

lgtm, i think the useEffect isn't needed though. do you mind updating the title of the PR to encompass the new changes?

[ncdiehl11]

lgtm, i think the useEffect isn't needed though. do you mind updating the title of the PR to encompass the new changes?

Confirming per our slack conversation that the useEffect is needed to preselect a single option on mount.