Improve DirWithoutEntrypoint error message (#3690)

Ran into this and couldn't tell what the problem was without the path
attached.

crates/uv-distribution/src/error.rs

@@ -1,4 +1,5 @@
 use std::path::PathBuf;
+
 use tokio::task::JoinError;
 use zip::result::ZipError;
 
@@ -7,6 +8,7 @@ use distribution_types::ParsedUrlError;
 use pep440_rs::Version;
 use pypi_types::HashDigest;
 use uv_client::BetterReqwestError;
+use uv_fs::Simplified;
 use uv_normalize::PackageName;
 
 #[derive(Debug, thiserror::Error)]
@@ -60,8 +62,8 @@ pub enum Error {
     DistInfo(#[from] install_wheel_rs::Error),
     #[error("Failed to read zip archive from built wheel")]
     Zip(#[from] ZipError),
-    #[error("Source distribution directory contains neither readable pyproject.toml nor setup.py")]
+    #[error("Source distribution directory contains neither readable pyproject.toml nor setup.py: `{}`", _0.user_display())]
-    DirWithoutEntrypoint,
+    DirWithoutEntrypoint(PathBuf),
     #[error("Failed to extract archive")]
     Extract(#[from] uv_extract::Error),
     #[error("Source distribution not found at: {0}")]

crates/uv-distribution/src/index/built_wheel_index.rs

@@ -105,7 +105,7 @@ impl<'a> BuiltWheelIndex<'a> {
         let Some(modified) =
             ArchiveTimestamp::from_source_tree(&source_dist.path).map_err(Error::CacheRead)?
         else {
-            return Err(Error::DirWithoutEntrypoint);
+            return Err(Error::DirWithoutEntrypoint(source_dist.path.clone()));
         };
 
         // If the distribution is stale, omit it from the index.

crates/uv-distribution/src/source/mod.rs

@@ -978,7 +978,7 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         let Some(modified) =
             ArchiveTimestamp::from_source_tree(&resource.path).map_err(Error::CacheRead)?
         else {
-            return Err(Error::DirWithoutEntrypoint);
+            return Err(Error::DirWithoutEntrypoint(resource.path.to_path_buf()));
         };
 
         // Read the existing metadata from the cache.