… while evaluating an attribute name

         error: value is a set while a string was expected
  ```

  Now, the error message displays where the problematic value was found:

  ```
  error:
         … while evaluating an attribute name

           at bad.nix:4:11:

              3|   key = {};
              4| in attr.${key}
               |           ^
              5|

         error: expected a string but found a set
  ```

- Some stack overflow segfaults are fixed [#9616](https://github.com/NixOS/nix/issues/9616) [#9617](https://github.com/NixOS/nix/pull/9617)

  The number of nested function calls has been restricted, to detect and report
  infinite function call recursions. The default maximum call depth is 10,000 and
  can be set with [the `max-call-depth`
  option](@docroot@/command-ref/conf-file.md#conf-max-call-depth).

  This replaces the `stack overflow (possible infinite recursion)` message.

- Better error reporting for `with` expressions [#9658](https://github.com/NixOS/nix/pull/9658)

  `with` expressions using non-attrset values to resolve variables are now reported with proper positions, e.g.

  ```
  nix-repl> with 1; a
  error:
         … while evaluating the first subexpression of a with expression
           at «string»:1:1:
              1| with 1; a
               | ^

         error: expected a set but found an integer
  ```

- Functions are printed with more detail [#7145](https://github.com/NixOS/nix/issues/7145) [#9606](https://github.com/NixOS/nix/pull/9606)

  `nix repl`, `nix eval`, `builtins.trace`, and most other places values are
  printed will now include function names and source location information:

  ```
  $ nix repl nixpkgs
  nix-repl> builtins.map
  «primop map»

  nix-repl> builtins.map lib.id
  «partially applied primop map»

  nix-repl> builtins.trace lib.id "my-value"
  trace: «lambda id @ /nix/store/8rrzq23h2zq7sv5l2vhw44kls5w0f654-source/lib/trivial.nix:26:5»
  "my-value"
  ```

- Flake operations like `nix develop` will no longer fail when run in a Git
  repository where the `flake.lock` file is `.gitignore`d
  [#8854](https://github.com/NixOS/nix/issues/8854)
  [#9324](https://github.com/NixOS/nix/pull/9324)

- Nix commands will now respect Ctrl-C
  [#7145](https://github.com/NixOS/nix/issues/7145)
  [#6995](https://github.com/NixOS/nix/pull/6995)
  [#9687](https://github.com/NixOS/nix/pull/9687)

  Previously, many Nix commands would hang indefinitely if Ctrl-C was pressed
  while performing various operations (including `nix develop`, `nix flake
  update`, and so on). With several fixes to Nix's signal handlers, Nix
  commands will now exit quickly after Ctrl-C is pressed.

- `nix copy` to a `ssh-ng` store now needs `--substitute-on-destination` (a.k.a. `-s`)
  in order to substitute paths on the remote store instead of copying them.
  The behavior is consistent with `nix copy` to a different kind of remote store.
  Previously this behavior was controlled by the
  `builders-use-substitutes` setting and `--substitute-on-destination` was ignored.