Firefox browserpass doesn't work, although enabled, messaging-hosts empty

[bwolf]

Describe the bug

I enabled programs.browserpass.enable = true; and also enabled Firefox with environment.systemPackages = [ pkgs.firefox ];. After that I installed the extension browserpass-extension (https://github.com/browserpass/browserpass-extension) into Firefox. When I click on the extension icon in Firefox it says "Error: Attempt to postMessage on disconnected port".

Steps To Reproduce

Steps to reproduce the behavior:

1. Enable programs.browserpass and have pass installed and configured
2. Install Firefox via environment.systemPackages
3. Install browserpass-extension into Firefox

Expected behavior

The extension connects to its native messaging host component.

Additional context

Although I enabled browserpass, and installed Firefox via systemPackages, the Firefox directory is missing the messaging host:

find (dirname (dirname (readlink (which firefox))))/lib/mozilla/native-messaging-hosts # note: fish syntax
/nix/store/64nhgp9hyqkfi8i2ky5pk5csjcpl459f-firefox-94.0.2/lib/mozilla/native-messaging-hosts

Metadata

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 5.15.4, NixOS, 22.05 (Quokka)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.5pre20211007_844dd90`
 - channels(root): `"nixos-21.05.4381.3bea86e918d"`
 - channels(marcus): `""`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos`

Not sure if it matters: I maintain my System with flakes: https://git.sr.ht/~bwolf/dotfiles/tree/master/item/flake.nix
It worked before I switched to unstable nixpkgs.

Maintainer information:

# a list of nixos modules affected by the problem
module: programs.browserpass