let binding with if dedents but without if indents

[jtojnar]

Input

let
  foo = if condition then null else
    4;

in
true

Output

let
  foo = if condition then null else
  4;

in
true

Desired output

let
  foo = if condition then null else
    4;

in
true

Since if I remove the if statement, the 4 will get indented again:

let
  foo =
    4;

in
true

Noticed in nixos/modules/services/x11/display-managers/gdm.nix on NixOS/nixpkgs#121490