Make route! macro auto-convert error types

`route!()` now calls `Groupped::to_chain()` on the error branch,
removing the need for callers to pre-convert with `.to_chain()` or
`.to_render()`.

6 files changed, 24 insertions, 13 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5384b45..b9b7bd7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -278,6 +278,16 @@ use mingling::{res::ResExitCode, res::ResREPL};
 
    Removed the per-type inherent method generation from both `groupped.rs` and `pack.rs` in `mingling_macros`.
 
+4. **\[macros\]** Changed the `route!()` macro's error branch from `return e` to `return ::mingling::Groupped::to_chain(e)`, so that the error type no longer needs to be pre-converted to `ChainProcess` via `.to_chain()` or `.to_render()`. The macro now accepts any type implementing `Groupped` in the error position and automatically converts it.
+
+```rust
+// Before
+let value = route!(prev.pick_or_route((), Error::default().to_chain()).unpack());
+
+// After
+let value = route!(prev.pick_or_route((), Error::default()).unpack());
+```
+
 ### Release 0.1.9 (2026-05-29)
 
 #### Fixes:
diff --git a/examples/example-argument-parse/src/main.rs b/examples/example-argument-parse/src/main.rs
index 316e52f..4929b7c 100644
--- a/examples/example-argument-parse/src/main.rs
+++ b/examples/example-argument-parse/src/main.rs
@@ -59,7 +59,7 @@ fn handle_strict_transfer_parse(args: EntryStrictTransfer) -> Next {
             .pick::<bool>(["--dir", "-D"])
             .pick_or::<usize>("--size", 1024 * 1024_usize)
             // Finally parse the positional argument; if not found, route to `ErrorNoNameProvided`
-            .pick_or_route::<String, _>((), ErrorNoNameProvided::default().to_chain())
+            .pick_or_route::<String, _>((), ErrorNoNameProvided::default())
             .after(|str| str.trim().replace(' ', ""))
             .unpack()
     }
diff --git a/examples/example-custom-pickable/src/main.rs b/examples/example-custom-pickable/src/main.rs
index a2aa662..015cc62 100644
--- a/examples/example-custom-pickable/src/main.rs
+++ b/examples/example-custom-pickable/src/main.rs
@@ -46,7 +46,7 @@ pack!(ErrorParseAddressFailed = ());
 #[chain]
 fn handle_connect(prev: EntryConnect) -> Next {
     let connect: Address =
-        route! { prev.pick_or_route((), ErrorParseAddressFailed::default().to_chain()).unpack() };
+        route! { prev.pick_or_route((), ErrorParseAddressFailed::default()).unpack() };
     connect.to_chain()
 }
 
diff --git a/examples/full-todolist/src/main.rs b/examples/full-todolist/src/main.rs
index fdac1c7..7f958d4 100644
--- a/examples/full-todolist/src/main.rs
+++ b/examples/full-todolist/src/main.rs
@@ -79,7 +79,7 @@ fn main() {
 fn handle_add(args: EntryAdd) -> Next {
     let task: String = route! {
         args
-            .pick_or_route((), ErrorNoTaskDescriptionProvided::new(()).to_render())
+            .pick_or_route((), ErrorNoTaskDescriptionProvided::new(()))
             .unpack()
     };
     StateAddTodo::new(task).to_chain()
@@ -119,7 +119,7 @@ fn handle_list(_args: EntryList, todolist: &mut LazyRes<ResTodoList>) -> Next {
 #[chain]
 fn handle_complete(args: EntryComplete) -> Next {
     let index: i32 = route! {
-        args.pick_or_route((), ErrorNoIndexProvided::new(()).to_render()).unpack()
+        args.pick_or_route((), ErrorNoIndexProvided::new(())).unpack()
     };
     StateCompleteTodo::new(index).to_chain()
 }
diff --git a/mingling/src/example_docs.rs b/mingling/src/example_docs.rs
index f77d9f6..caa12ae 100644
--- a/mingling/src/example_docs.rs
+++ b/mingling/src/example_docs.rs
@@ -79,7 +79,7 @@
 ///             .pick::<bool>(["--dir", "-D"])
 ///             .pick_or::<usize>("--size", 1024 * 1024_usize)
 ///             // Finally parse the positional argument; if not found, route to `ErrorNoNameProvided`
-///             .pick_or_route::<String, _>((), ErrorNoNameProvided::default().to_chain())
+///             .pick_or_route::<String, _>((), ErrorNoNameProvided::default())
 ///             .after(|str| str.trim().replace(' ', ""))
 ///             .unpack()
 ///     }
@@ -670,7 +670,7 @@ pub mod example_completion {}
 /// #[chain]
 /// fn handle_connect(prev: EntryConnect) -> Next {
 ///     let connect: Address =
-///         route! { prev.pick_or_route((), ErrorParseAddressFailed::default().to_chain()).unpack() };
+///         route! { prev.pick_or_route((), ErrorParseAddressFailed::default()).unpack() };
 ///     connect.to_chain()
 /// }
 ///
diff --git a/mingling_macros/src/lib.rs b/mingling_macros/src/lib.rs
index 204d59c..3b33f09 100644
--- a/mingling_macros/src/lib.rs
+++ b/mingling_macros/src/lib.rs
@@ -405,12 +405,13 @@ pub fn pack_err(input: TokenStream) -> TokenStream {
 /// ```rust,ignore
 /// match expr {
 ///     Ok(r) => r,
-///     Err(e) => return e,
+///     Err(e) => return ::mingling::Groupped::to_chain(e),
 /// }
 /// ```
 ///
-/// It is useful inside chain functions where you have a `Result<ChainProcess<G>, ChainProcess<G>>`
-/// and want to propagate the error case as an early return.
+/// It is useful inside chain functions where you have a `Result<SomeType, SomeType>`
+/// where both types implement `Groupped` and want to propagate the error case
+/// as an early return via `Groupped::to_chain()`.
 ///
 /// # Example
 ///
@@ -419,9 +420,9 @@ pub fn pack_err(input: TokenStream) -> TokenStream {
 ///
 /// #[chain]
 /// fn process(prev: SomeEntry) -> ChainProcess<ThisProgram> {
-///     let value = route!(try_something().ok_or(ErrorEntry::new("failed".into()).to_render()));
-///     // value is the Ok(ChainProcess) from try_something()
-///     value
+///     let value = route!(current_dir().map_err(|e| ErrorEntry::new(e.to_string_lossy().to_string())));
+///     // value is the PathBuf from current_dir()
+///     value.to_chain()
 /// }
 /// ```
 #[cfg(feature = "extra_macros")]
@@ -431,7 +432,7 @@ pub fn route(input: TokenStream) -> TokenStream {
     let expanded = quote! {
         match #expr {
             Ok(r) => r,
-            Err(e) => return e,
+            Err(e) => return ::mingling::Groupped::to_chain(e),
         }
     };
     TokenStream::from(expanded)