diff --git a/seeds/pythonboard/src/breadboard.py b/seeds/pythonboard/src/breadboard.py
index 653b3ca2..02478591 100644
--- a/seeds/pythonboard/src/breadboard.py
+++ b/seeds/pythonboard/src/breadboard.py
@@ -156,7 +156,10 @@ async def run(
       if type(handler) == javascript.proxy.Proxy:
         # This can possibly be wrapped in an AsyncTask instead of a trivial coroutine
         async def await_js(func, args):
-          res = func(args)
+          if func.invoke:
+            res = func.invoke(args)
+          else:
+            res = func(args)
           # Outputs can be a javascript proxy, so convert to dict
           try:
             res = {k: res[k] for k in res}
diff --git a/seeds/pythonboard/src/traversal/iterator.py b/seeds/pythonboard/src/traversal/iterator.py
index c9c82d4a..cd2b0685 100644
--- a/seeds/pythonboard/src/traversal/iterator.py
+++ b/seeds/pythonboard/src/traversal/iterator.py
@@ -45,13 +45,22 @@ def _processCompletedNode(
     if outputs.get("$error") and not any(e.out == "$error" for e in newOpportunities):
       # If the node threw an exception and it wasn't routed via $error,
       # throw it again. This will cause the traversal to stop.
-      raise Exception(
-        "Uncaught exception in node handler. " +
-          "Catch by wiring up the $error output.",
-        {
-          "cause": outputs["$error"],
-        }
-      )
+      if isinstance(outputs.get("$error").error, Exception):
+        raise Exception(
+          "Uncaught exception in node handler. " +
+            "Catch by wiring up the $error output.",
+          {
+            "cause": outputs["$error"],
+          }
+        ) from outputs.get("$error").error
+      else:
+        raise Exception(
+          "Uncaught exception in node handler. " +
+            "Catch by wiring up the $error output.",
+          {
+            "cause": outputs["$error"],
+          }
+        )
 
   @staticmethod
   async def processAllPendingNodes(
@@ -89,7 +98,8 @@ async def _promise():
           # If not already present, add inputs and descriptor along for
           # context and to support retries.
           if "$error" in outputs:
-            outputs["$error"] = outputs["$error"] | {
+            error_dict = {k: outputs["$error"][k] for k in outputs["$error"]}
+            outputs["$error"] = error_dict | {
               "descriptor": descriptor,
               "inputs": inputs,
             }