revert 83ec5a063a

revert vars: use writeShellApplication to shellcheck generators

Cannot re-generate the vars for data-mesher or any of our tests anymore

cc @DavHau @Qubasa Can we work together to fix this.
I like shellchecking but if we loose the ability to add tests thats unfortunate
This is blocking: the new 'restic' and 'zerotier' migrations because we need to write integration tests from the beginning.

nixosModules/clanCore/vars/generator.nix

@@ -16,7 +16,7 @@ let
     ;
 
   promptToFile = name: ''
-    cat "$prompts"/${name} > "$out"/${name}
+    cat "$prompts/${name}" > "$out/${name}"
   '';
 
   promptsToFilesScript = concatMapStrings promptToFile;
@@ -25,13 +25,8 @@ let
 in
 {
   finalScript = mkOptionDefault (
-    lib.getExe (
-      pkgs.writeShellApplication {
-        name = "generator-${config.name}";
-        text = ''
-          in="''${in:?}"
-          out="''${out:?}"
-          ${if config.prompts == { } then "" else ''prompts="''${prompts:?}"''}
+    pkgs.writeScript "generator-${config.name}" ''
+      set -eu -o pipefail
 
       export PATH="${makeBinPath config.runtimeInputs}:${pkgs.coreutils}/bin"
 
@@ -58,9 +53,7 @@ in
       ''}
       ${promptsToFilesScript filePromptNames}
       ${config.script}
-        '';
-      }
-    )
+    ''
   );
 
   files = genAttrs filePromptNames (_name: { });