Form names cannot be numbers

Goal: submitted form returns saved values in numerical order like:

Name: hunterdg
1: answer to Q1
2: answer to Q2

---

Originally I struggled to create simple numbered form fields at all due to `("Trying to access array offset on value of type int")`.

fields:
- name: 1
- name: '2'

---

I found that prefixing numbers with `.` works _for rendering_, but nut for submitted form data

fields:
- name: Name
- name: '.1'
- name: '.2'
- name: ' 3'
- name: ' 4'

returns

Name: hunterdg
.1: null
.2: null
3: 3
4: 4

(3 and 4 are prefixed with spaces)

Is this a bug or should I work around it?

Start with the YAML examples in the issue and trace how numeric field names are handled during rendering and form submission. Reproduce the difference between numeric, dot-prefixed, and space-prefixed names; done means numbered fields render and submitted values preserve the intended names and answers.

Written by the indexing model from the issue text.