## Changes
Before this change, any error in a subtree would cause the entire
subtree to be dropped from the output.
This is not ideal when debugging, so instead we drop only the values
that cannot be normalized. Note that this doesn't change behavior if the
caller is properly checking the returned diagnostics for errors.
Note: this includes a change to use `dyn.InvalidValue` as opposed to
`dyn.NilValue` when returning errors.
## Tests
Added unit tests for the case where nested struct, map, or slice
elements contain an error.
## Changes
The name "dynamic value", or "dyn" for short, is more descriptive than
the opaque "config". Also, it conveniently does not alias with other
packages in the repository, or (popular ones) elsewhere.
(discussed with @andrewnester)
## Tests
n/a
Pieter Noordhuis