pvp：修复可能会匹配到自己的问题

game-server/app/services/pvpService.ts

@@ -146,6 +146,7 @@ export async function matchPlayerByRank(seasonNum: number, chosenOpps: string[],
             }
         }
     }
+    if(oppRank <= 0) return null;
     let result = await r.getUserByRank(oppRank);
     if (result.length <= 0) return null;
     oppRoleId = result[0];