JS API cannot read numeric array columns, such as from DISTINCT in a UI-created rollup

[niloc132]

Display a table with some numeric array columns, such as via a rollup with a distinct agg:

Steps to reproduce:

1. Create a table with a column that can be grouped, and a column to aggregate by distinct in the rollup

   from deephaven import empty_table
   t = empty_table(100).update(["A = i % 3", "B = i % 7"])

2. In the web IDE, open the advanced options > rollup rows, and group by one of the columns
3. Then open the aggregate columns view and specify "distinct" for remaining columns

Expected: data is visible in the UI
Actual: No data loads (and no error shows, see browser console for details)

Uncaught Error: java.lang.ClassCastException
    createError dh-core.js:1464
    initializeBackingError dh-core.js:1490
    Throwable_0 dh-core.js:1421
    Exception_1 dh-core.js:1515
    RuntimeException_1 dh-core.js:1533
    ClassCastException_0 dh-core.js:40658
    checkCriticalType dh-core.js:49930
    castTo dh-core.js:324
    asObjectChunk dh-core.js:5204
    contract_7 dh-core.js:11368
    $readChunk_7 dh-core.js:10900
    readChunk_9 dh-core.js:10954
    $parseFrom dh-core.js:21237
    $onFlightData dh-core.js:28343
    apply_144 dh-core.js:28508
    lambda dh-core.js:193
    doExchange dh-internal.js:1

Found while testing #6200
Should be fixed by #6065