TOML migration issue

[BenWibking]

I ran into an issue when updating all of our input files to be TOML-conformant (following #4950).

For existing arrays, I switched them to use parmparse_list_name = [0, 1, 2] syntax instead of parmparse_list_name = 0 1 2.

However, this causes a crash with get("parmparse_list_name", value, i), because i can index into the list 0 1 2, but not into [0, 1, 2].

What is the right fix for this case?

cc @WeiqunZhang

[WeiqunZhang]

We could add support for TOML arrays in that get function.

[WeiqunZhang]

See #5149.