In the case of Hammer v. Breidenbach, 31 Mo. 49 (1860), Mr. Breidenbach was hired to brew beer in a cave for his employer, at a salary of $1,000 per year. The contract between the Bavarian Brewery (which would later become Anheuser-Busch) and Mr. Breidenbach specified that any violation of the agreement would result in the breaching party paying the sum of $500 to the injured party. Because the cave was dangerous, Mr. Breidenbach refused to enter it to make the beer, and his employer demanded the $500. An appellate court later determined that Mr. Breidenbach should not be required to enter the cave and endanger himself, and he was not required to pay the $500 "penalty." In which of the following modern cases could this case act as an appropriate precedent