fix: reject unsafe version cleanup windows

docs/src/js/classes/Table.md

@@ -587,6 +587,9 @@ Modeled after ``VACUUM`` in PostgreSQL.
  you have added or modified 100,000 or more records or run more than 20 data
  modification operations.
 
+ Cleanup retention must exceed the longest expected write. Retention shorter
+ than 10 minutes requires `deleteUnverified: true` and exclusive write access.
+
 #### Parameters
 
 * **options?**: `Partial`<[`OptimizeOptions`](../interfaces/OptimizeOptions.md)>

docs/src/js/interfaces/OptimizeOptions.md

@@ -16,7 +16,10 @@ cleanupOlderThan: Date;
 
 If set then all versions older than the given date
 be removed.  The current version will never be removed.
-The default is 7 days
+The default is 7 days. The resulting retention period must be longer than
+the longest expected write. Values shorter than 10 minutes require
+`deleteUnverified: true` and are only safe when no other process can write
+to the dataset.
 
 #### Example
 
@@ -26,8 +29,8 @@ const olderThan = new Date();
 olderThan.setDate(olderThan.getDate() - 1));
 tbl.optimize({cleanupOlderThan: olderThan});
 
-// Delete all versions except the current version
-tbl.optimize({cleanupOlderThan: new Date()});
+// With exclusive access, delete all versions except the current version
+tbl.optimize({cleanupOlderThan: new Date(), deleteUnverified: true});
 ```
 
 ***