feat(tvix/nix-compat): Use StorePath in Output

https: //b.tvl.fyi/issues/264
Change-Id: Icb09be9643245cc68d09f01d7723af2d44d6bd1a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11001
Autosubmit: Peter Kolloch <info@eigenvalue.net>
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

tvix/nix-compat/src/derivation/errors.rs

@@ -53,6 +53,8 @@ pub enum DerivationError {
 pub enum OutputError {
     #[error("Invalid output path {0}: {1}")]
     InvalidOutputPath(String, store_path::Error),
+    #[error("Missing output path")]
+    MissingOutputPath,
     #[error("Invalid CAHash: {:?}", .0)]
     InvalidCAHash(CAHash),
 }