Fix TableViewportSubscription race condition (deephaven#3252)

- Race condition was causing UI error with selectDistinct
- TableViewportSubscription could initialize after it had already been closed
- Check the status to see if we're already DONE before initializing
- Close table if we're already DONE
- Fixes deephaven#3251

web/client-api/src/main/java/io/deephaven/web/client/api/subscription/TableViewportSubscription.java

@@ -109,9 +109,13 @@ public TableViewportSubscription(double firstRow, double lastRow, Column[] colum
         this.original = existingTable;
         this.originalState = original.state();
         copy = existingTable.copy(false).then(table -> new Promise<>((resolve, reject) -> {
-
             // Wait until the state is running to copy it
             originalState.onRunning(newState -> {
+                if (this.status == Status.DONE) {
+                    JsLog.debug("TableViewportSubscription closed before originalState.onRunning completed, ignoring");
+                    table.close();
+                    return;
+                }
                 table.batch(batcher -> {
                     batcher.customColumns(newState.getCustomColumns());
                     batcher.filter(newState.getFilters());