Index: Cargo.toml
==================================================================
--- Cargo.toml
+++ Cargo.toml
@@ -1,8 +1,8 @@
 [package]
 name = "qsu"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2021"
 license = "0BSD"
 categories = [ "asynchronous" ]
 keywords = [ "service", "systemd", "winsvc" ]
 repository = "https://repos.qrnch.tech/pub/qsu"
@@ -28,11 +28,11 @@
 rt = []
 tokio = ["rt", "tokio/macros", "tokio/rt-multi-thread", "tokio/signal"]
 wait-for-debugger = ["dep:dbgtools-win"]
 
 [dependencies]
-apperr = { version = "0.1.0" }
+apperr = { version = "0.2.0" }
 async-trait = { version = "0.1.77" }
 chrono = { version = "0.4.31" }
 clap = { version = "4.4.14", optional = true, features = [
   "derive", "env", "string", "wrap_help"
 ] }

Index: examples/err/mod.rs
==================================================================
--- examples/err/mod.rs
+++ examples/err/mod.rs
@@ -5,10 +5,11 @@
   IO(String),
   Qsu(String)
 }
 
 impl std::error::Error for Error {}
+impl apperr::Blessed for Error {}
 
 impl fmt::Display for Error {
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
     match self {
       Error::IO(s) => {

Index: src/err.rs
==================================================================
--- src/err.rs
+++ src/err.rs
@@ -81,25 +81,31 @@
 
   /// Attempt to convert [`Error`] into application-specific error.
   ///
   /// If it's not an `Error::App()` nor can be downcast to type `E`, the error
   /// will be returned back as an `Err()`.
-  pub fn try_into_apperr<E: 'static>(self) -> Result<E, Error> {
+  pub fn try_into_apperr<E>(self) -> Result<E, Error>
+  where
+    E: std::error::Error + apperr::Blessed + 'static
+  {
     match self {
       Error::App(e) => match e.try_into_inner::<E>() {
         Ok(e) => Ok(e),
-        Err(e) => Err(Error::App(AppErr::new(e)))
+        Err(e) => Err(Error::App(e))
       },
       e => Err(e)
     }
   }
 
   /// Unwrap application-specific error from an [`Error`].
   ///
   /// # Panic
   /// Panics if `Error` variant is not `Error::App()`.
-  pub fn unwrap_apperr<E: 'static>(self) -> E {
+  pub fn unwrap_apperr<E>(self) -> E
+  where
+    E: std::error::Error + apperr::Blessed + 'static
+  {
     let Ok(e) = self.try_into_apperr::<E>() else {
       panic!("Unable to unwrap error E");
     };
     e
   }

Index: src/rt.rs
==================================================================
--- src/rt.rs
+++ src/rt.rs
@@ -74,14 +74,24 @@
 //! callbacks to return application-defined errors using the regular question
 //! mark, it may be helpful to add the following error conversion to the error
 //! module:
 //!
 //! ```
+//! use std::fmt;
+//!
 //! // Application-specific Error type
+//! #[derive(Debug)]
 //! enum Error {
 //!   // .. application-defined error variants
 //! }
+//! impl fmt::Display for Error {
+//!   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+//!     Ok(())
+//!   }
+//! }
+//! impl std::error::Error for Error {}
+//! impl apperr::Blessed for Error {}
 //!
 //! impl From<Error> for qsu::AppErr {
 //!   fn from(err: Error) -> qsu::AppErr {
 //!     qsu::AppErr::new(err)
 //!   }

Index: tests/err/mod.rs
==================================================================
--- tests/err/mod.rs
+++ tests/err/mod.rs
@@ -6,10 +6,11 @@
   IO(String),
   Qsu(String)
 }
 
 impl std::error::Error for Error {}
+impl apperr::Blessed for Error {}
 
 impl Error {
   pub fn hello(msg: impl ToString) -> Self {
     Error::Hello(msg.to_string())
   }

Index: www/changelog.md
==================================================================
--- www/changelog.md
+++ www/changelog.md
@@ -3,10 +3,13 @@
 ## [Unreleased]
 
 ### Added
 
 ### Changed
+
+- Use apperr 0.2.0, which introduces trait bounds to the `AppErr::new(E)` to
+  make it more difficult to pass the wrong type to it.
 
 ### Removed
 
 ---