3 files changed, 73 insertions, 50 deletions

diff --git a/cli/tests/unit/dispatch_bin_test.ts b/cli/tests/unit/dispatch_bin_test.ts
index ca1864621..54a379bc0 100644
--- a/cli/tests/unit/dispatch_bin_test.ts
+++ b/cli/tests/unit/dispatch_bin_test.ts
@@ -1,27 +1,16 @@
-import {
-  assert,
-  assertEquals,
-  assertMatch,
-  unitTest,
-  unreachable,
-} from "./test_util.ts";
+import { assertStringIncludes, unitTest, unreachable } from "./test_util.ts";
 
-const readErrorStackPattern = new RegExp(
-  `^.*
-    at processErr \\(.*core\\.js:.*\\)
-    at opAsyncHandler \\(.*core\\.js:.*\\)
-    at handleAsyncMsgFromRust \\(.*core\\.js:.*\\).*$`,
-  "ms",
-);
-
-unitTest(async function sendAsyncStackTrace(): Promise<void> {
+unitTest(async function sendAsyncStackTrace() {
   const buf = new Uint8Array(10);
   const rid = 10;
   try {
     await Deno.read(rid, buf);
     unreachable();
   } catch (error) {
-    assertMatch(error.stack, readErrorStackPattern);
+    const s = error.stack.toString();
+    console.log(s);
+    assertStringIncludes(s, "dispatch_bin_test.ts");
+    assertStringIncludes(s, "read");
   }
 });
 
diff --git a/core/core.js b/core/core.js
index 3ec5c3e41..3142aa93a 100644
--- a/core/core.js
+++ b/core/core.js
@@ -65,7 +65,10 @@
 
   function handleAsyncMsgFromRust() {
     for (let i = 0; i < arguments.length; i += 2) {
-      opAsyncHandler(arguments[i], arguments[i + 1]);
+      const promiseId = arguments[i];
+      const res = arguments[i + 1];
+      const promise = getPromise(promiseId);
+      promise.resolve(res);
     }
   }
 
@@ -84,48 +87,31 @@
     return errorMap[errorName] ?? [undefined, []];
   }
 
-  function processResponse(res) {
-    if (!isErr(res)) {
-      return res;
-    }
-    throw processErr(res);
-  }
-
-  // .$err_class_name is a special key that should only exist on errors
-  function isErr(res) {
-    return !!(res && res.$err_class_name);
-  }
-
-  function processErr(err) {
-    const className = err.$err_class_name;
-    const [ErrorClass, args] = getErrorClassAndArgs(className);
-    if (!ErrorClass) {
-      return new Error(
-        `Unregistered error class: "${className}"\n  ${err.message}\n  Classes of errors returned from ops should be registered via Deno.core.registerErrorClass().`,
-      );
+  function unwrapOpResult(res) {
+    // .$err_class_name is a special key that should only exist on errors
+    if (res?.$err_class_name) {
+      const className = res.$err_class_name;
+      const [ErrorClass, args] = getErrorClassAndArgs(className);
+      if (!ErrorClass) {
+        throw new Error(
+          `Unregistered error class: "${className}"\n  ${res.message}\n  Classes of errors returned from ops should be registered via Deno.core.registerErrorClass().`,
+        );
+      }
+      throw new ErrorClass(res.message, ...args);
     }
-    return new ErrorClass(err.message, ...args);
+    return res;
   }
 
   function jsonOpAsync(opName, args = null, zeroCopy = null) {
     const promiseId = nextPromiseId++;
     const maybeError = dispatch(opName, promiseId, args, zeroCopy);
     // Handle sync error (e.g: error parsing args)
-    if (maybeError) processResponse(maybeError);
-    return setPromise(promiseId);
+    if (maybeError) return unwrapOpResult(maybeError);
+    return setPromise(promiseId).then(unwrapOpResult);
   }
 
   function jsonOpSync(opName, args = null, zeroCopy = null) {
-    return processResponse(dispatch(opName, null, args, zeroCopy));
-  }
-
-  function opAsyncHandler(promiseId, res) {
-    const promise = getPromise(promiseId);
-    if (!isErr(res)) {
-      promise.resolve(res);
-    } else {
-      promise.reject(processErr(res));
-    }
+    return unwrapOpResult(dispatch(opName, null, args, zeroCopy));
   }
 
   function binOpSync(opName, args = null, zeroCopy = null) {
diff --git a/core/ops_json.rs b/core/ops_json.rs
index 21c6b219f..0efd44a90 100644
--- a/core/ops_json.rs
+++ b/core/ops_json.rs
@@ -108,3 +108,51 @@ where
     },
   )
 }
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[tokio::test]
+  async fn json_op_async_stack_trace() {
+    let mut runtime = crate::JsRuntime::new(Default::default());
+
+    async fn op_throw(
+      _state: Rc<RefCell<OpState>>,
+      msg: Option<String>,
+      zero_copy: Option<ZeroCopyBuf>,
+    ) -> Result<(), AnyError> {
+      assert_eq!(msg.unwrap(), "hello");
+      assert!(zero_copy.is_none());
+      Err(crate::error::generic_error("foo"))
+    }
+
+    runtime.register_op("op_throw", json_op_async(op_throw));
+    runtime
+      .execute(
+        "<init>",
+        r#"
+    // First we initialize the ops cache. This maps op names to their id's.
+    Deno.core.ops();
+    // Register the error class.
+    Deno.core.registerErrorClass('Error', Error);
+
+    async function f1() {
+      await Deno.core.jsonOpAsync('op_throw', 'hello');
+    }
+
+    async function f2() {
+      await f1();
+    }
+
+    f2();
+    "#,
+      )
+      .unwrap();
+    let e = runtime.run_event_loop().await.unwrap_err().to_string();
+    println!("{}", e);
+    assert!(e.contains("Error: foo"));
+    assert!(e.contains("at async f1 (<init>:"));
+    assert!(e.contains("at async f2 (<init>:"));
+  }
+}