direnv: hopefully final nushell fix

modules/programs/direnv.nix

@@ -130,10 +130,32 @@ in {
         ${getExe cfg.package} hook fish | source
       '');
 
-    programs.nushell.extraConfig = mkIf cfg.enableNushellIntegration (
+    programs.nushell.extraConfig = mkIf cfg.enableNushellIntegration (let
+      # We want to get the stdout from direnv even if it exits with non-zero,
+      # because it will have the DIRENV_ internal variables defined.
+      #
+      # However, nushell's current implementation of try-catch is subtly
+      # broken with external commands in pipelines[0].
+      #
+      # This means we don't have a good way to ignore the exit code
+      # without using do | complete, which has a side effect of also
+      # capturing stderr, which we don't want.
+      #
+      # So, as a workaround, we wrap nushell in a second script that
+      # just ignores the exit code and does nothing else, allowing
+      # nushell to capture our stdout, but letting stderr go through
+      # and not causing a spurious "command failed" message.
+      #
+      # [0]: https://github.com/nushell/nushell/issues/13868
+      #
+      # FIXME: remove the wrapper once the upstream issue is fixed
+
+      direnvWrapped = pkgs.writeShellScript "direnv-wrapped" ''
+        ${getExe cfg.package} export json || true
+      '';
       # Using mkAfter to make it more likely to appear after other
       # manipulations of the prompt.
-      mkAfter ''
+    in mkAfter ''
       $env.config = ($env.config? | default {})
       $env.config.hooks = ($env.config.hooks? | default {})
       $env.config.hooks.pre_prompt = (
@@ -141,11 +163,7 @@ in {
           | default []
           | append {||
               let direnv = (
-                    # We want to get the stdout from direnv even if it exits with non-zero,
+                  ${direnvWrapped}
-                    # because it will have the DIRENV_ internal variables defined.
-                    do --ignore-program-errors { ${
-                      getExe cfg.package
-                    } export json }
                   | from json --strict
                   | default {}
               )

tests/modules/programs/direnv/nushell.nix

@@ -13,6 +13,6 @@
       "home-files/.config/nushell/config.nu";
   in ''
     assertFileExists "${configFile}"
-    assertFileRegex "${configFile}" '/nix/store/.*direnv.*/bin/direnv export json'
+    assertFileRegex "${configFile}" '/nix/store/.*direnv-wrapped'
   '';
 }