deephaven.ui stock rollup example doesn't work

[mofojed]

Description

Run the Stock Rollup example from https://github.com/deephaven/deephaven-plugins/tree/main/plugins/ui/examples#stock-rollup, and you get some weird errors. You can also do a minimal example to reproduce:

from deephaven import empty_table, ui

t1 = empty_table(100).update("x=i")
t2 = empty_table(100).update("y=i")

@ui.component
def bad_component():
    clicked, set_clicked = ui.use_state(False)

    return [
        ui.toggle_button("Switch Table", on_change=set_clicked),
        t2 if clicked else t1
    ]

bc = bad_component()

Steps to reproduce

1. Run the following snippet:

from deephaven import empty_table, ui

t1 = empty_table(100).update("x=i")
t2 = empty_table(100).update("y=i")

@ui.component
def bad_component():
    clicked, set_clicked = ui.use_state(False)

    return [
        ui.toggle_button("Switch Table", on_change=set_clicked),
        t2 if clicked else t1
    ]

bc = bad_component()

2. Click on the "Switch Table" button to switch between two tables

Expected results
2. Table should switch

Actual results
2. Table switches once but then does not switch back. An error in the browser console logs:

An unexpected error occurred while executing "documentUpdated" JSON-RPC method: Error: Invalid exported object key 0
    at Array.eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:5926:19)
    at JSON.parse (<anonymous>)
    at eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:5913:31)
    at eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:5977:29)
    at eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4787:24)
    at callMethod (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4892:18)
    at noopMiddleware (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4924:10)
    at JSONRPCServer2.callMethod (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4904:51)
    at JSONRPCServer2.eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4853:31)
    at step (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4727:19)
    at Object.eval [as next] (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4674:14)
    at eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4660:67)
    at new Promise (<anonymous>)
    at __awaiter$1 (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4642:10)
    at JSONRPCServer2.receiveSingle (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4843:14)
    at JSONRPCServer2.receive (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4816:21)
    at JSONRPCServerAndClient2.eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:5120:38)
    at step (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:5045:19)
    at Object.eval [as next] (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4992:14)
    at eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4978:67)
    at new Promise (<anonymous>)
    at __awaiter (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:4960:10)
    at JSONRPCServerAndClient2.receiveAndSend (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:5108:14)
    at receiveData (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:5996:48)
    at eval (eval at <anonymous> (loadRemoteModule.ts:42:20), <anonymous>:6004:9)
    at Object.$lambda$3 (dh-core.js:8217:5)
    at Function.onInvoke_12 (dh-core.js:8935:16)
    at lambda (dh-core.js:174:22)
    at Array.forEach (<anonymous>)
    at Object.$fireEvent_0 (dh-core.js:8193:15)
    at Object.$lambda$6_5 (dh-core.js:28705:11)
    at Function.apply_170 (dh-core.js:28932:10)
    at lambda (dh-core.js:174:22)
    at dh-internal.js:1:818486
    at Array.forEach (<anonymous>)
    at dh-internal.js:1:818465
    at dh-internal.js:1:43546
    at Array.forEach (<anonymous>)
    at e.rawOnMessage (dh-internal.js:1:43508)
    at dh-internal.js:1:41321
    at Array.forEach (<anonymous>)
    at e.onTransportChunk (dh-internal.js:1:41196)
    at Object.$onMessage (dh-core.js:21056:35)
    at MultiplexedWebsocketTransport$3methodref$onMessage$Type.handleEvent_2 [as handleEvent] (dh-core.js:21200:10)

Additional details and attachments
It seems client is throwing the object out because it no longer had a reference to it, but server still had it cached. Should be more explicit about when an exported object is no longer needed or is re-used. Probably just need the server to only keep the object IDs from the last render, and not current renders.
Only matters for exported objects, since we need the actual object client side to fetch the child data. Callables should be safe to use the weak key, since the client will just call the callback by ID.

Versions

deephaven.ui v0.6.0