Do not over-prune var data cache (#1198)

* Remove unused variables and imports

* Simplify conditional

* Fix typo

* Do not overprune var data cache

There is a bug in how the universe and world gene sets are constructed
and passed to `ControlsHelpers.pruneVarDataCache` that causes the var
data cache to be over-pruned. This commit fixes the issue.

Consider the following example from the node console:

```
❯ node
Welcome to Node.js v13.5.0.
Type ".help" for more information.
> new Set([1], [2], [3])
Set(1) { 1 }
```

What we really want is the set `Set(3) { 1, 2, 3 }`, which can be
constructed as:

```
> new Set([].concat([1], [2], [3]))
Set(3) { 1, 2, 3 }
```

client/src/reducers/undoableConfig.js

@@ -145,7 +145,7 @@ Signature:  (fsm, event, from) => undoableAction
 const onFsmError = (fsm, event, from) => {
   console.error(`FSM error [event: "${event}", state: "${from}"]`, fsm);
   // In production, try to recover gracefully if we have unexpected state
-  return clear(fsm);
+  return clear();
 };
 
 /*