fix: Exit on communication failure (#429)

fixes #430

Often when rerunning component creation, an error containing "Stream is
already completed, no further calls are allowed" comes up
```
Error rendering __main__.test_component
Traceback (most recent call last):
  File "/Users/josephnumainville/Documents/deephaven-core/.venv/lib/python3.10/site-packages/deephaven/ui/object_types/ElementMessageStream.py", line 159, in _render
    self._send_document_update(node, state)
  File "/Users/josephnumainville/Documents/deephaven-core/.venv/lib/python3.10/site-packages/deephaven/ui/object_types/ElementMessageStream.py", line 355, in _send_document_update
    self._connection.on_data(payload.encode(), new_objects)
  File "/Users/josephnumainville/Documents/deephaven-core/.venv/lib/python3.10/site-packages/deephaven_internal/plugin/object/__init__.py", line 47, in on_data
    self._wrapped.onData(payload, [javaify(ref) for ref in references])
RuntimeError: io.deephaven.plugin.type.ObjectCommunicationException: java.lang.IllegalStateException: Stream is already completed, no further calls are allowed
...
```

This doesn't need to raise an exception to the user as this is just the
previous component's message stream signaling it is closed, but it does
need to exit so it doesn't keep trying to hit the message stream.

plugins/ui/src/deephaven/ui/object_types/ElementMessageStream.py

@@ -2,6 +2,8 @@
 
 import io
 import json
+import sys
+
 from jsonrpc import JSONRPCResponseManager, Dispatcher
 import logging
 import threading
@@ -119,6 +121,11 @@ class ElementMessageStream(MessageStream):
     Captured ExecutionContext for this stream, to wrap all user code.
     """
 
+    _is_closed: bool
+    """
+    Whether or not the stream is closed. If closed, no more messages can be sent, and this component should exit.
+    """
+
     def __init__(self, element: Element, connection: MessageStream):
         """
         Create a new ElementMessageStream. Renders the element in a render context, and sends the rendered result to the
@@ -142,6 +149,7 @@ def __init__(self, element: Element, connection: MessageStream):
         self._is_dirty = False
         self._render_state = _RenderState.IDLE
         self._exec_context = get_exec_ctx()
+        self._is_closed = False
 
     def _render(self) -> None:
         logger.debug("ElementMessageStream._render")
@@ -240,7 +248,7 @@ def start(self) -> None:
         self._connection.on_data(b"", [])
 
     def on_close(self) -> None:
-        pass
+        self._is_closed = True
 
     def on_data(self, payload: bytes, references: list[Any]) -> None:
         """
@@ -352,4 +360,9 @@ def _send_document_update(
             logger.debug("Registering callable %s", callable_id)
             dispatcher[callable_id] = wrap_callable(callable)
         self._dispatcher = dispatcher
+        if self._is_closed:
+            # The connection is closed, so this component will not update anymore
+            # delete the context so the objects in the collected scope are released
+            del self._context
+            sys.exit()
         self._connection.on_data(payload.encode(), new_objects)