Query: “what date did nixon resign”
Instant answer: “August 8, 1974,”
Note the trailing comma on 1974. This is likely because it's in the text that Kagi pulled from, from https://www.archivesfoundation.org/documents/richard-nixon-resignation-letter-gerald-ford-pardon/ (emphasis mine):
On the evening of August 8, 1974, President Nixon addressed the nation and announced his intention to resign. The next morning, White House Chief of Staff Alexander Haig presented this letter to President Nixon to sign. The President’s resignation letter is addressed to Secretary of State Henry Kissinger, who initialed it at 11:35 a.m.
I think Kagi should strip these trailing punctuations or, even better, understand that they're not part of the answer in the first place.
