Missing return value check for EnumerableSet .add() and .remove() operations

In the GenesisLicenseStaking.sol contract, the EnumerableSet utility functions .add() and .remove() from OpenZeppelin's library are used in multiple places to manage sets (for example, of stakers, token IDs, pools).

However, these functions return a bool indicating whether the operation succeeded:

• .add() returns false if the element was already present.
• .remove() returns false if the element was not in the set.

These return values are currently not checked, meaning:

• A failed .add() might falsely imply a new addition.
• A failed .remove() could lead to assumptions that the element was deleted when it wasn't.

This could result in inconsistent state assumptions, misleading bookkeeping, and incorrect logic execution downstream.

Subtle accounting errors are possible. For example, attempting to remove an index that is not in the queue will silently succeed without removing anything, leaving downstream state inconsistent.

Update all calls to .add() and .remove() to check their return value, and explicitly revert() on failure if the logic depends on the success of the operation.