What is the legal issue and rules that apply to this case?

Stacey contracts to buy six cases of vintage Stomp Valley wine from Twisted Winery for $1,200. The contract states that delivery is to be made at Stacey’s residence “on or before May 1, to be used for daughter’s wedding reception on May 2.” On May 1, Twisted’s delivery van is involved in an accident, and no wine is delivered that day. A message was left for Stacy telling her of the accident. On the morning of May 2, Stacey buys the wine from Happy Hill Winery for $1,800, and her staff prepares for the reception. That afternoon, just before the reception, Twisted tenders delivery of the wine at Stacey’s residence. She refuses tender. Twisted sues Stacey for breach of contract, Stacy files a counter claim.