Evidence of:

a valuable consideration in compromising or attempting to compromise a claim which was disputed as to either validity or amount is not admissible to prove liability for the claim, invalidity of the claim or the amount of the claim.

Evidence of conduct or statements made in compromise negotiations is not admissible. This section does not require the exclusion of discoverable evidence merely because it is revealed in the course of compromise negotiations. This section does not require exclusion of evidence when it is offered for another purpose, including proof of bias or prejudice of a witness, negativing a contention of undue delay, or proof of an effort to obstruct a criminal investigation or prosecution.