Nil check battle and classic session count

.gitignore

@@ -1,4 +1,5 @@
 
-pokerogue-server.exe
+# no extension on linux, .exe on windows
+pokerogue-server*
 userdata/*
 secret.key

db/game.go

@@ -12,7 +12,7 @@ func FetchPlayerCount() (int, error) {
 
 func FetchBattleCount() (int, error) {
 	var battleCount int
-	err := handle.QueryRow("SELECT SUM(battles) FROM accountStats").Scan(&battleCount)
+	err := handle.QueryRow("SELECT COALESCE(SUM(battles), 0) FROM accountStats").Scan(&battleCount)
 	if err != nil {
 		return 0, err
 	}
@@ -22,7 +22,7 @@ func FetchBattleCount() (int, error) {
 
 func FetchClassicSessionCount() (int, error) {
 	var classicSessionCount int
-	err := handle.QueryRow("SELECT SUM(classicSessionsPlayed) FROM accountStats").Scan(&classicSessionCount)
+	err := handle.QueryRow("SELECT COALESCE(SUM(classicSessionsPlayed), 0) FROM accountStats").Scan(&classicSessionCount)
 	if err != nil {
 		return 0, err
 	}