I've done the same as BN.
I line it out and then by my signature write, "as ammended"
I actually have in our band's contract that the band is not responsibly for any actions of the guests, patrons, fans, or any damage they might do.
You would be surprised what some venues want you to agree to.
I remember renting a garage from someone so to protect my car from damage on the street in the city. They wanted in the contract that they were not responsible for damage to my car. Huh? then what's the point of renting the garage?
I am entertainment/copyright attorney. As a musician, I've signed plenty of contracts that had an indemnity provision.
Often, musicians are asked to sign boilerplate agreements with extremely broad language. With an indemnity provision you're agreeing to compensate the venue (I.e. the library) in the event they're sued due to your own negligence (this is the "hold harmless"). For instance, if you carelessly leave all of your instrument cases in a high foot traffic area and someone trips and is injured, you're agreeing to reimburse the library for damages if they are sued successfully in court.
As an independent musician you usually lack leverage to negotiate this clause. It can still be done, with limited success. Changes to their boilerplate can soften your obligations and liability.
Remember that in practice, an indie musician is a not a very attractive target for someone wanting to initiate a lawsuit for damages.
It's great that you're reading your contracts. Keep in mind, though, that there are other provisions of a performance agreement that merit much closer inspection.