chore(tvix/eval): print node representation for compiler errors

Better for development flow.

Change-Id: I038efb39caca804f28a44fd4c83457e90abbcee4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6290
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>

tvix/eval/src/eval.rs

@@ -42,7 +42,11 @@ pub fn interpret(code: &str, location: Option<PathBuf>) -> EvalResult<Value> {
     }
 
     for error in &result.errors {
-        eprintln!("compiler error: {:?} at {:?}", error.kind, error.node,);
+        eprintln!(
+            "compiler error: {:?} at {:?}",
+            error.kind,
+            error.node.as_ref().map(|node| node.text())
+        );
     }
 
     if let Some(err) = result.errors.last() {