Cannot set a numeric property on an object

[majidkorai]

I am following the code example given here on readme.md
I am getting the error as in the subject.

Interestingly if I append some letter before priting the field name it works.

name={${fieldName}.name} - this doesn't work.
name={a${fieldName}.name} this works. (notice I appended letter a)

Note I can confirm my fieldName is NOT numeric. its a string.

Are you submitting a bug report or a feature request?

What is the current behavior?

What is the expected behavior?

Sandbox Link

What's your environment?

Other information

[majidkorai]

I figured it out. It was happening because I was validating the field. I removed the validation and it started working.