require
Retrieves the address associated with the given blockchain chain.
This function first attempts to get the address using getAddress. If an address is found, it's returned. If no address is found (i.e., getAddress returns null), an IllegalArgumentException is thrown, indicating that no address is available for the specified chain.
Return
The address as a String if found.
Parameters
chain
The PortalNamespace representing the blockchain for which to retrieve the address.
Throws
If no address is found for the specified chain.