# Description
Our config exists both as a `Config` struct for internal consumption and
as a `Value`. The latter is exposed through `$env.config` and can be
both set and read.
Thus we have a complex bug-prone mechanism, that reads a `Value` and
then tries to plug anything where the value is unrepresentable in
`Config` with the correct state from `Config`.

The parsing involves therefore mutation of the `Value` in a nested
`Record` structure. Previously this was wholy done manually, with
indices.
To enable deletion for example, things had to be iterated over from the
back. Also things were indexed in a bunch of places. This was hard to
read and an invitation for bugs.

With #10876 we can now use `Record::retain_mut` to traverse the records,
modify anything that needs fixing, and drop invalid fields.

# Parts:

- Error messages now consistently use the correct spans pointing to the
problematic value and the paths displayed in some messages are also
aligned with the keys used for lookup.
- Reconstruction of values has been fixed for:
	- `table.padding`
	- `buffer_editor`
	- `hooks.command_not_found`
	- `datetime_format` (partial solution)
- Fix validation of `table.padding` input so value is not set (and
underflows `usize` causing `table` to run forever with negative values)
- New proper types for settings. Fully validated enums instead of
strings:
  - `config.edit_mode` -> `EditMode` 
  	- Don't fall back to vi-mode on invalid string
  - `config.table.mode` -> `TableMode`
- there is still a fall back to `rounded` if given an invalid
`TableMode` as argument to the `nu` binary
  - `config.completions.algorithm` -> `CompletionAlgorithm`
  - `config.error_style` -> `ErrorStyle`
    - don't implicitly fall back to `fancy` when given an invalid value.
- This should also shrink the size of `Config` as instead of 4x24 bytes
those fields now need only 4x1 bytes in `Config`
- Completely removed macros relying on the scope of `Value::into_config`
so we can break it up into smaller parts in the future.
- Factored everything into smaller files with the types and helpers for
particular topics.
- `NuCursorShape` now explicitly expresses the `Inherit` setting.
conversion to option only happens at the interface to `reedline`

# Description
While we have now a few ways to add items or iterate over the
collection, we don't have a way to cleanly remove items from `Record`.

This PR fixes that:

- Add `Record.remove()` to remove by key
- makes the assumption that keys are unique, so can not be used
universally, yet (see nushell#10875 for an important example)
- Add naive `Record.retain()` for inplace removal
- This follows the two separate `retain`/`retain_mut` in the Rust std
library types, compared to the value-mutating `retain` in `indexmap`
- Add `Record.retain_mut()` for one-pass pruning

Continuation of nushell#10841 

# User-Facing Changes
None yet.

# Tests + Formatting
Doctests for the `retain`ing fun

# Description
Our config exists both as a `Config` struct for internal consumption and
as a `Value`. The latter is exposed through `$env.config` and can be
both set and read.
Thus we have a complex bug-prone mechanism, that reads a `Value` and
then tries to plug anything where the value is unrepresentable in
`Config` with the correct state from `Config`.

The parsing involves therefore mutation of the `Value` in a nested
`Record` structure. Previously this was wholy done manually, with
indices.
To enable deletion for example, things had to be iterated over from the
back. Also things were indexed in a bunch of places. This was hard to
read and an invitation for bugs.

With nushell#10876 we can now use `Record::retain_mut` to traverse the records,
modify anything that needs fixing, and drop invalid fields.

# Parts:

- Error messages now consistently use the correct spans pointing to the
problematic value and the paths displayed in some messages are also
aligned with the keys used for lookup.
- Reconstruction of values has been fixed for:
	- `table.padding`
	- `buffer_editor`
	- `hooks.command_not_found`
	- `datetime_format` (partial solution)
- Fix validation of `table.padding` input so value is not set (and
underflows `usize` causing `table` to run forever with negative values)
- New proper types for settings. Fully validated enums instead of
strings:
  - `config.edit_mode` -> `EditMode` 
  	- Don't fall back to vi-mode on invalid string
  - `config.table.mode` -> `TableMode`
- there is still a fall back to `rounded` if given an invalid
`TableMode` as argument to the `nu` binary
  - `config.completions.algorithm` -> `CompletionAlgorithm`
  - `config.error_style` -> `ErrorStyle`
    - don't implicitly fall back to `fancy` when given an invalid value.
- This should also shrink the size of `Config` as instead of 4x24 bytes
those fields now need only 4x1 bytes in `Config`
- Completely removed macros relying on the scope of `Value::into_config`
so we can break it up into smaller parts in the future.
- Factored everything into smaller files with the types and helpers for
particular topics.
- `NuCursorShape` now explicitly expresses the `Inherit` setting.
conversion to option only happens at the interface to `reedline`

# Description
While we have now a few ways to add items or iterate over the
collection, we don't have a way to cleanly remove items from `Record`.

This PR fixes that:

- Add `Record.remove()` to remove by key
- makes the assumption that keys are unique, so can not be used
universally, yet (see nushell#10875 for an important example)
- Add naive `Record.retain()` for inplace removal
- This follows the two separate `retain`/`retain_mut` in the Rust std
library types, compared to the value-mutating `retain` in `indexmap`
- Add `Record.retain_mut()` for one-pass pruning

Continuation of nushell#10841 

# User-Facing Changes
None yet.

# Tests + Formatting
Doctests for the `retain`ing fun

# Description
Our config exists both as a `Config` struct for internal consumption and
as a `Value`. The latter is exposed through `$env.config` and can be
both set and read.
Thus we have a complex bug-prone mechanism, that reads a `Value` and
then tries to plug anything where the value is unrepresentable in
`Config` with the correct state from `Config`.

The parsing involves therefore mutation of the `Value` in a nested
`Record` structure. Previously this was wholy done manually, with
indices.
To enable deletion for example, things had to be iterated over from the
back. Also things were indexed in a bunch of places. This was hard to
read and an invitation for bugs.

With nushell#10876 we can now use `Record::retain_mut` to traverse the records,
modify anything that needs fixing, and drop invalid fields.

# Parts:

- Error messages now consistently use the correct spans pointing to the
problematic value and the paths displayed in some messages are also
aligned with the keys used for lookup.
- Reconstruction of values has been fixed for:
	- `table.padding`
	- `buffer_editor`
	- `hooks.command_not_found`
	- `datetime_format` (partial solution)
- Fix validation of `table.padding` input so value is not set (and
underflows `usize` causing `table` to run forever with negative values)
- New proper types for settings. Fully validated enums instead of
strings:
  - `config.edit_mode` -> `EditMode` 
  	- Don't fall back to vi-mode on invalid string
  - `config.table.mode` -> `TableMode`
- there is still a fall back to `rounded` if given an invalid
`TableMode` as argument to the `nu` binary
  - `config.completions.algorithm` -> `CompletionAlgorithm`
  - `config.error_style` -> `ErrorStyle`
    - don't implicitly fall back to `fancy` when given an invalid value.
- This should also shrink the size of `Config` as instead of 4x24 bytes
those fields now need only 4x1 bytes in `Config`
- Completely removed macros relying on the scope of `Value::into_config`
so we can break it up into smaller parts in the future.
- Factored everything into smaller files with the types and helpers for
particular topics.
- `NuCursorShape` now explicitly expresses the `Inherit` setting.
conversion to option only happens at the interface to `reedline`