v8: add and use log_traceback

crates/core/src/host/v8/error.rs

@@ -126,7 +126,9 @@ pub(super) struct JsError {
 impl fmt::Display for JsError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         writeln!(f, "js error {}", self.msg)?;
-        writeln!(f, "{}", self.trace)?;
+        if !f.alternate() {
+            writeln!(f, "{}", self.trace)?;
+        }
         Ok(())
     }
 }
@@ -249,6 +251,16 @@ impl JsError {
     }
 }
 
+pub(super) fn log_traceback(func_type: &str, func: &str, e: &anyhow::Error) {
+    log::info!("{func_type} \"{func}\" runtime error: {e:#}");
+    if let Some(js_err) = e.downcast_ref::<JsError>() {
+        log::info!("js error {}", js_err.msg);
+        for (index, frame) in js_err.trace.frames.iter().enumerate() {
+            log::info!("  Frame #{index}: {frame}");
+        }
+    }
+}
+
 /// Run `body` within a try-catch context and capture any JS exception thrown as a [`JsError`].
 pub(super) fn catch_exception<'scope, T>(
     scope: &mut HandleScope<'scope>,

crates/core/src/host/v8/mod.rs

@@ -12,7 +12,7 @@ use crate::{host::Scheduler, module_host_context::ModuleCreationContext, replica
 use anyhow::anyhow;
 use core::time::Duration;
 use de::deserialize_js;
-use error::{catch_exception, exception_already_thrown, ExcResult, Throwable};
+use error::{catch_exception, exception_already_thrown, log_traceback, ExcResult, Throwable};
 use from_value::cast;
 use key_cache::get_or_create_key_cache;
 use ser::serialize_to_js;
@@ -157,8 +157,7 @@ impl ModuleInstance for JsInstance {
             &self.replica_ctx.clone(),
             tx,
             params,
-            // TODO(centril): logging.
-            |_ty, _fun, _err| {},
+            log_traceback,
             |tx, op, _budget| {
                 let call_result = call_call_reducer_from_op(scope, op);
                 // TODO(centril): energy metrering.