feat(engines): do not silence manifest read errors

Now reading the manifest will only be silenced if
the error's cause is the manifest not being found.

src/main.rs

@@ -286,11 +286,13 @@ async fn run() -> anyhow::Result<()> {
 			break 'engines;
 		};
 
-		let req = project
+		let req = match project.deser_manifest().await {
-			.deser_manifest()
+			Ok(mut manifest) => manifest.engines.remove(&engine),
-			.await
+			Err(pesde::errors::ManifestReadError::Io(e)) if e.kind() == io::ErrorKind::NotFound => {
-			.ok()
+				None
-			.and_then(|mut manifest| manifest.engines.remove(&engine));
+			}
+			Err(e) => return Err(e.into()),
+		};
 
 		if engine == EngineKind::Pesde {
 			match &req {