Improve error handling for which::which failures

Co-authored-by: Pascal Kuthe <pascalkuthe@pm.me>

helix-dap/src/client.rs

@@ -113,7 +113,7 @@ impl Client {
         id: usize,
     ) -> Result<(Self, UnboundedReceiver<Payload>)> {
         // Resolve path to the binary
-        let cmd = helix_stdx::env::which(cmd).map_err(|err| anyhow::anyhow!(err))?;
+        let cmd = helix_stdx::env::which(cmd)?;
 
         let process = Command::new(cmd)
             .args(args)

helix-dap/src/lib.rs

@@ -19,6 +19,8 @@ pub enum Error {
     #[error("server closed the stream")]
     StreamClosed,
     #[error(transparent)]
+    ExecutableNotFound(#[from] helix_stdx::env::ExecutableNotFoundError),
+    #[error(transparent)]
     Other(#[from] anyhow::Error),
 }
 pub type Result<T> = core::result::Result<T, Error>;