CClient::getProperty

Description: Gets a client property from $this-$>$clientInfo and dies (or returns an error value), if this property is not set.
Parameter:

• key: Name of the property.
• dieMessage: Message to show before dying.
• return: This will returned in case of an error, if set to another value, than 'null'.

Returns:

• Value of the property (or error value).