improve the error message around incorrect worktree paths

Author: Byron

gix/src/config/mod.rs

@@ -91,8 +91,11 @@ pub enum Error {
     ResolveIncludes(#[from] gix_config::file::includes::Error),
     #[error(transparent)]
     FromEnv(#[from] gix_config::file::init::from_env::Error),
-    #[error(transparent)]
-    PathInterpolation(#[from] gix_config::path::interpolate::Error),
+    #[error("The path {path:?} at the 'core.worktree' configuration could not be interpolated")]
+    PathInterpolation {
+        path: BString,
+        source: gix_config::path::interpolate::Error,
+    },
     #[error("{source:?} configuration overrides at open or init time could not be applied.")]
     ConfigOverrides {
         #[source]

gix/src/open/repository.rs

@@ -237,9 +237,13 @@ impl ThreadSafeRepository {
                 .resolved
                 .path_filter("core", None, Core::WORKTREE.name, &mut filter_config_section)
             {
+                let wt_clone = wt.clone();
                 let wt_path = wt
                     .interpolate(interpolate_context(git_install_dir.as_deref(), home.as_deref()))
-                    .map_err(config::Error::PathInterpolation)?;
+                    .map_err(|err| config::Error::PathInterpolation {
+                        path: wt_clone.value.into_owned(),
+                        source: err,
+                    })?;
                 worktree_dir = gix_path::normalize(git_dir.join(wt_path).into(), current_dir).map(Cow::into_owned);
                 #[allow(unused_variables)]
                 if let Some(worktree_path) = worktree_dir.as_deref().filter(|wtd| !wtd.is_dir()) {

gix/tests/repository/open.rs

@@ -74,7 +74,7 @@ fn non_bare_split_worktree_invalid_worktree_path_empty() -> crate::Result {
     )
     .unwrap_err();
     assert!(
-            matches!(err, gix::open::Error::Config(gix::config::Error::PathInterpolation(_))),
+            matches!(err, gix::open::Error::Config(gix::config::Error::PathInterpolation{..})),
             "DEVIATION: could not read path at core.worktree as empty is always invalid, git tries to use an empty path, even though it's better to reject it"
         );
     Ok(())