refactor(tvix/derivation): use DerivationError in Output::validate

Change-Id: I7dbd3b8ff9ef92acddde2e579fb24b8311c34d8f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7852
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/derivation/src/validate.rs

@@ -39,11 +39,8 @@ impl Derivation {
             }
 
             if let Err(e) = output.validate() {
-                return Err(DerivationError::InvalidOutputPath(
-                    output_name.to_string(),
-                    e,
-                ));
-            };
+                return Err(DerivationError::InvalidOutput(output_name.to_string(), e));
+            }
         }
 
         // Validate all input_derivations