refine my errors

src/NixStore.zig

@@ -4,41 +4,37 @@ const std = @import("std");
 
 const gpa = std.heap.page_allocator;
 
-const NixStoreError = error{
+pub fn add(path: []const u8) error{Failure}![]const u8 {
-    Failure,
-};
-
-pub fn add(path: []const u8) NixStoreError![]const u8 {
     const res = std.process.Child.run(.{
         .allocator = gpa,
         .argv = &[_][]const u8{ "nix", "store", "add", path },
-    }) catch return NixStoreError.Failure;
+    }) catch return error.Failure;
 
     return res.stdout[0 .. res.stdout.len - 1]; // to chop off the \n
 }
 
-pub fn realize(store_path: []const u8) NixStoreError!void {
+pub fn realize(store_path: []const u8) error{Failure}!void {
     _ = std.process.Child.run(.{
         .allocator = gpa,
         .argv = &[_][]const u8{ "nix-store", "--realize", store_path },
-    }) catch return NixStoreError.Failure;
+    }) catch return error.Failure;
     return;
 }
 
-pub fn root(store_path: []const u8, root_path: []const u8) NixStoreError!void {
+pub fn root(store_path: []const u8, root_path: []const u8) error{Failure}!void {
     _ = std.process.Child.run(.{
         .allocator = gpa,
         .argv = &[_][]const u8{ "nix-store", "--add-root", root_path, "--indirect", store_path },
-    }) catch return NixStoreError.Failure;
+    }) catch return error.Failure;
     return;
 }
 
-pub fn delete(store_path: []const u8) NixStoreError!void {
+pub fn delete(store_path: []const u8) error{Failure}!void {
     _ = std.process.Child.run(.{
         .allocator = gpa,
         .argv = &[_][]const u8{ "nix", "store", "delete", store_path },
     }) catch {
-        return NixStoreError.Failure;
+        return error.Failure;
     };
     return;
 }

src/main.zig

@@ -102,7 +102,7 @@ pub fn main() !void {
     // delete the old nix store path
     if (dest_old_store_path) |path| {
         std.log.info("deleting old store path: {s}", .{path});
-        NixStore.delete(path) catch |err| if (err == error.Failure) return err;
+        try NixStore.delete(path);
     }
 }