usually you may report a bug and hope to get some short of reward for your white hat action on the matter. However that is strictly voluntary for the site, so no guarantee. Another way to go about it is try to reach a deal with the site, still risky unless you get a third party escrow into the matter. Ideally casinos should have a permanent bug-hunting programme altogether, but... no easy way for this despite looking quite obvious they should.
Subsequently, on that basis, it is good to note that bugs have varieties and what they hold on the site, if it has to do with a less technical aspect, the site may decide not to pay anything for them since it believes at that stage the it based on features that do not have direct implications and application on games that are listed on the casino.
Aside from that, other bugs have to do with the game system which if left intended could lead to a high degree of impact on the game realities and results, this level of bug is treated with high attention and casinos will easily pay bounty or compensation for those who will report them.