Fix tournament page crashing when a DE bracket with a follow-up bracket has exactly 2 teams

app/features/tournament-bracket/core/Bracket/DoubleEliminationBracket.ts

@@ -124,12 +124,12 @@ export class DoubleEliminationBracket extends Bracket {
 		}
 
 		// edge case: 1 match only
-		const noLosersRounds = !losersGroupId;
+		const noLosersRounds = losersGroupId === undefined;
 		const grandFinalsNumber = noLosersRounds ? 1 : 3;
 		const grandFinalsGroupId = this.data.group.find(
 			(g) => g.number === grandFinalsNumber,
 		)?.id;
-		invariant(grandFinalsGroupId, "GF group not found");
+		invariant(grandFinalsGroupId !== undefined, "GF group not found");
 		const grandFinalMatches = this.data.match.filter(
 			(match) => match.groupId === grandFinalsGroupId,
 		);
@@ -137,6 +137,7 @@ export class DoubleEliminationBracket extends Bracket {
 		// if opponent1 won in DE it means that bracket reset is not played
 		if (
 			grandFinalMatches[0].opponent1 &&
+			grandFinalMatches[0].winnerSide &&
 			(noLosersRounds || grandFinalMatches[0].winnerSide === "opponent1")
 		) {
 			const loser =
@@ -163,7 +164,7 @@ export class DoubleEliminationBracket extends Bracket {
 				team: winnerTeam,
 				placement: 1,
 			});
-		} else if (grandFinalMatches[1].winnerSide) {
+		} else if (grandFinalMatches[1]?.winnerSide) {
 			const loser =
 				grandFinalMatches[1].winnerSide === "opponent1"
 					? "opponent2"

app/features/tournament-bracket/core/Tournament.test.ts

@@ -204,6 +204,19 @@ describe("Follow-up bracket progression", () => {
 		}
 	});
 
+	test("initializes an unstarted DE + underground tournament with exactly 2 teams", () => {
+		const tournament = testTournament({
+			ctx: {
+				settings: {
+					bracketProgression: progressions.doubleEliminationWithUnderground,
+				},
+				teams: [tournamentCtxTeam(1), tournamentCtxTeam(2)],
+			},
+		});
+
+		expect(tournament.brackets).toHaveLength(2);
+	});
+
 	// TODO: handle LUTI bracket progression
 	// test("avoids rematches in RR -> SE (LUTI S16 Div 1) - avoid as long as possible", () => {
 	// 	https://github.com/sendou-ink/sendou.ink/pull/2192