Error with empty columns in labels file

[sarahcd]

Describe the bug
Linking a labels file that includes all columns described in the manual gives an error if some columns are not filled in.
https://ecodata-animate.readthedocs.io/en/latest/user_guide/user_guide.html#labeled-points

To Reproduce
Steps to reproduce the behavior:

1. In the Labeled points tab, upload a csv like the following:

longitude,latitude,label,start_time,end_time,label_longitude,label_latitude,horizontal_alignment
-116,50,test,,,,,

2. Click 'Create animation'.
3. See error

Expected behavior
I'm not sure which of the empty columns must be filled out, but removing them to create a csv like this succeeded:

longitude,latitude,label
-116,50,test

Ideally, empty columns could be ignored, to avoid having to troubleshoot errors if columns are un/populated while preparing an animation. If not, we should at least identify which ones must be populated, and then can update the manual accordingly.

Error log

Error using fillmissing>checkArrayType (line 952)
Fill constant must be numeric or logical.

Error in fillmissing (line 201)

Error in prepare_labels (line 17)

Error in animate_tracks (line 68)

Error in animator/CreateanimationButtonPushed (line 565)

Error in appdesigner.internal.service.AppManagementService/executeCallback (line 172)

Error in matlab.apps.AppBase>@(source,event)executeCallback(ams,app,callback,requiresEventData,event) (line 62)

Software information (please complete the following information):

• ECODATA Animate 1.2.3
• MacBook Pro 15.1.1 (24B91)