refactor(errors)!: Improve error handling, display and clean up codeb…

…ase (#321)

- Grouped imports for better organization: `ErrorKind`, `RusticError`, `RusticResult`
- Fixed and updated tests for new error handling logic
- Addressed Clippy lints and improved code quality
- Ensured build compatibility for *nix and OSX platforms
- Updated function documentation to reflect new error handling
- Removed unused local error variants after refactor
- Verified `rustic-rs` functionality against the updated branch

Cargo.toml

@@ -12,14 +12,19 @@ resolver = "2"
 rust-version = "1.76.0"
 
 [workspace.dependencies]
+# Internal Dependencies
+rustic_backend = { path = "crates/backend", version = "0" }
+rustic_core = { path = "crates/core", version = "0" }
+rustic_testing = { path = "crates/testing", version = "0" }
+
 aho-corasick = "1.1.3"
 anyhow = "1.0.89"
 bytes = "1.7.2"
+displaydoc = "0.2.5"
 enum-map = "2.7.3"
-rustic_backend = { path = "crates/backend" }
-rustic_core = { path = "crates/core", version = "0" }
-rustic_testing = { path = "crates/testing", version = "0" }
+log = "0.4.22"
 simplelog = "0.12.2"
+thiserror = "2.0.0"
 
 # dev-dependencies
 rstest = "0.23.0"

crates/backend/Cargo.toml

@@ -50,15 +50,14 @@ rclone = ["rest", "dep:rand", "dep:semver"]
 rustic_core = { workspace = true }
 
 # errors
-anyhow = "1.0.89"
-displaydoc = "0.2.5"
-thiserror = "1.0.64"
+displaydoc = { workspace = true }
+thiserror = { workspace = true }
 
 # logging
-log = "0.4.22"
+log = { workspace = true }
 
 # other dependencies
-bytes = "1.7.2"
+bytes = { workspace = true }
 derive_setters = "0.1.6"
 humantime = "2.1.0"
 itertools = "0.13.0"
@@ -101,6 +100,7 @@ opendal = { version = "0.50.0", features = ["services-b2", "services-sftp", "ser
 opendal = { version = "0.50.0", features = ["services-b2", "services-swift", "services-azblob", "services-azdls", "services-cos", "services-fs", "services-ftp", "services-dropbox", "services-gdrive", "services-gcs", "services-ghac", "services-http", "services-ipmfs", "services-memory", "services-obs", "services-onedrive", "services-oss", "services-s3", "services-webdav", "services-webhdfs", "services-azfile", "layers-blocking", "layers-throttle"], optional = true }
 
 [dev-dependencies]
+anyhow = { workspace = true }
 rstest = { workspace = true }
 toml = "0.8.19"
 

crates/backend/src/choose.rs

@@ -1,14 +1,11 @@
 //! This module contains [`BackendOptions`] and helpers to choose a backend from a given url.
-use anyhow::{anyhow, Result};
 use derive_setters::Setters;
 use std::{collections::HashMap, sync::Arc};
 use strum_macros::{Display, EnumString};
 
-#[allow(unused_imports)]
-use rustic_core::{RepositoryBackends, WriteBackend};
+use rustic_core::{ErrorKind, RepositoryBackends, RusticError, RusticResult, WriteBackend};
 
 use crate::{
-    error::BackendAccessErrorKind,
     local::LocalBackend,
     util::{location_to_type_and_path, BackendLocation},
 };
@@ -75,12 +72,17 @@ impl BackendOptions {
     /// # Returns
     ///
     /// The backends for the repository.
-    pub fn to_backends(&self) -> Result<RepositoryBackends> {
+    pub fn to_backends(&self) -> RusticResult<RepositoryBackends> {
         let mut options = self.options.clone();
         options.extend(self.options_cold.clone());
         let be = self
             .get_backend(self.repository.as_ref(), options)?
-            .ok_or_else(|| anyhow!("No repository given."))?;
+            .ok_or_else(|| {
+                RusticError::new(
+                    ErrorKind::Backend,
+                    "No repository given. Please make sure, that you have set the repository.",
+                )
+            })?;
         let mut options = self.options.clone();
         options.extend(self.options_hot.clone());
         let be_hot = self.get_backend(self.repo_hot.as_ref(), options)?;
@@ -97,7 +99,7 @@ impl BackendOptions {
     ///
     /// # Errors
     ///
-    /// If the backend cannot be loaded, an error is returned.
+    /// * If the backend cannot be loaded, an error is returned.
     ///
     /// # Returns
     ///
@@ -108,13 +110,18 @@ impl BackendOptions {
         &self,
         repo_string: Option<&String>,
         options: HashMap<String, String>,
-    ) -> Result<Option<Arc<dyn WriteBackend>>> {
+    ) -> RusticResult<Option<Arc<dyn WriteBackend>>> {
         repo_string
             .map(|string| {
                 let (be_type, location) = location_to_type_and_path(string)?;
-                be_type.to_backend(location, options.into()).map_err(|err| {
-                    BackendAccessErrorKind::BackendLoadError(be_type.to_string(), err).into()
-                })
+                be_type
+                    .to_backend(location.clone(), options.into())
+                    .map_err(|err| {
+                        err
+                        .prepend_guidance_line("Could not load the backend `{name}` at `{location}`. Please check the given backend and try again.")
+                        .attach_context("name", be_type.to_string())
+                        .attach_context("location", location.to_string())
+                    })
             })
             .transpose()
     }
@@ -131,14 +138,12 @@ pub trait BackendChoice {
     ///
     /// # Errors
     ///
-    /// * [`BackendAccessErrorKind::BackendNotSupported`] - If the backend is not supported.
-    ///
-    /// [`BackendAccessErrorKind::BackendNotSupported`]: crate::error::BackendAccessErrorKind::BackendNotSupported
+    /// * If the backend is not supported.
     fn to_backend(
         &self,
         location: BackendLocation,
         options: Option<HashMap<String, String>>,
-    ) -> Result<Arc<dyn WriteBackend>>;
+    ) -> RusticResult<Arc<dyn WriteBackend>>;
 }
 
 /// The supported backend types.
@@ -176,7 +181,7 @@ impl BackendChoice for SupportedBackend {
         &self,
         location: BackendLocation,
         options: Option<HashMap<String, String>>,
-    ) -> Result<Arc<dyn WriteBackend>> {
+    ) -> RusticResult<Arc<dyn WriteBackend>> {
         let options = options.unwrap_or_default();
 
         Ok(match self {

crates/backend/src/lib.rs

@@ -53,27 +53,22 @@ This crate exposes a few features for controlling dependency usage:
 */
 
 pub mod choose;
-/// Error types for the backend.
-pub mod error;
 /// Local backend for Rustic.
 pub mod local;
+/// Utility functions for the backend.
+pub mod util;
+
 /// `OpenDAL` backend for Rustic.
 #[cfg(feature = "opendal")]
 pub mod opendal;
+
 /// `Rclone` backend for Rustic.
 #[cfg(feature = "rclone")]
 pub mod rclone;
+
 /// REST backend for Rustic.
 #[cfg(feature = "rest")]
 pub mod rest;
-/// Utility functions for the backend.
-pub mod util;
-
-// rustic_backend Public API
-pub use crate::{
-    choose::{BackendOptions, SupportedBackend},
-    local::LocalBackend,
-};
 
 #[cfg(feature = "opendal")]
 pub use crate::opendal::OpenDALBackend;
@@ -83,3 +78,12 @@ pub use crate::rclone::RcloneBackend;
 
 #[cfg(feature = "rest")]
 pub use crate::rest::RestBackend;
+
+// rustic_backend Public API
+pub use crate::{
+    choose::{BackendOptions, SupportedBackend},
+    local::LocalBackend,
+};
+
+// re-export for error handling
+pub use rustic_core::{ErrorKind, RusticError, RusticResult, Severity, Status};