feat(modules.makeWrapper): allow null values in env and envDefault to remove entries

ci/checks/env-null.nix

@@ -0,0 +1,38 @@
+{
+  pkgs,
+  self,
+}:
+
+let
+  wrappedPackage = self.lib.wrapPackage {
+    inherit pkgs;
+    package = pkgs.hello;
+    env.MY_NULL_ENV = null;
+    envDefault.MY_NULL_DEFAULT = null;
+  };
+
+in
+pkgs.runCommand "env-null-test" { } ''
+  echo "Testing that null env and envDefault entries are omitted..."
+
+  wrapperScript="${wrappedPackage}/bin/hello"
+  if [ ! -f "$wrapperScript" ]; then
+    echo "FAIL: Wrapper script not found"
+    exit 1
+  fi
+
+  if grep -q "MY_NULL_ENV" "$wrapperScript"; then
+    echo "FAIL: MY_NULL_ENV should be omitted (value was null)"
+    cat "$wrapperScript"
+    exit 1
+  fi
+
+  if grep -q "MY_NULL_DEFAULT" "$wrapperScript"; then
+    echo "FAIL: MY_NULL_DEFAULT should be omitted (value was null)"
+    cat "$wrapperScript"
+    exit 1
+  fi
+
+  echo "SUCCESS: null env and envDefault entries correctly omitted"
+  touch $out
+''

lib/makeWrapper/default.nix

@@ -368,7 +368,9 @@ in
         ++ mapAndLiftDal "addFlag" (config.addFlag or [ ])
         ++ mapAndLiftDal "appendFlag" (config.appendFlag or [ ]);
     in
-    if sortResult then wlib.dag.unwrapSort "makeWrapper" unsorted else unsorted;
+    builtins.filter (v: !(v.type == "env" || v.type == "envDefault") || v.data or null != null) (
+      if sortResult then wlib.dag.unwrapSort "makeWrapper" unsorted else unsorted
+    );
 
   /*
     splitDal receives the dal as returned by `aggregateSingleOptionSet` and splits it into 2 lists, `args` and `other`.

modules/makeWrapper/module.nix

@@ -408,7 +408,7 @@ let
           ];
         };
       options.${if !(excluded.env or false) then "env" else null} = lib.mkOption {
-        type = wlib.types.dagWithEsc wlib.types.stringable;
+        type = wlib.types.dagWithEsc (lib.types.nullOr wlib.types.stringable);
         default = if mainConfig != null && config.mirror or false then mainConfig.env else { };
         example = {
           "XDG_DATA_HOME" = "/somewhere/on/your/machine";
@@ -425,7 +425,7 @@ let
         '';
       };
       options.${if !(excluded.envDefault or false) then "envDefault" else null} = lib.mkOption {
-        type = wlib.types.dagWithEsc wlib.types.stringable;
+        type = wlib.types.dagWithEsc (lib.types.nullOr wlib.types.stringable);
         default = if mainConfig != null && config.mirror or false then mainConfig.envDefault else { };
         example = {
           "XDG_DATA_HOME" = "/only/if/not/set";