fix nil pointer dereference for valid demo (#162)

we just assume it's a bot since all human players were parsed correctly
in the demo where this problem was encountered.

Author: markus-wa

common/player.go

@@ -49,6 +49,7 @@ type Player struct {
 	IsDefusing                  bool
 	IsPlanting                  bool
 	IsReloading                 bool
+	IsUnknown                   bool // Used to identify unknown/broken players. see https://github.com/markus-wa/demoinfocs-golang/issues/162
 	HasDefuseKit                bool
 	HasHelmet                   bool
 }

datatables.go

@@ -193,21 +193,33 @@ func (p *Parser) bindNewPlayer(playerEntity st.IEntity) {
 	isNew := false
 	pl := p.gameState.playersByEntityID[entityID]
 	if pl == nil {
-		pl = p.gameState.playersByUserID[rp.userID]
+		if rp != nil {
+			pl = p.gameState.playersByUserID[rp.userID]
 
-		if pl == nil {
-			isNew = true
+			if pl == nil {
+				isNew = true
 
-			// TODO: read tickRate from CVARs as fallback
+				pl = common.NewPlayer(p.demoInfoProvider)
+				pl.Name = rp.name
+				pl.SteamID = rp.xuid
+				pl.IsBot = rp.isFakePlayer || rp.guid == "BOT"
+				pl.UserID = rp.userID
+			}
+		} else {
+			// see #162.
+			// GOTV doesn't crash here either so we just initialize this player with default values.
+			// this happens in some demos since November 2019 for players that were are actually connected.
+			// in GOTV these players are just called "unknown".
 			pl = common.NewPlayer(p.demoInfoProvider)
-			pl.Name = rp.name
-			pl.SteamID = rp.xuid
-			pl.IsBot = rp.isFakePlayer || rp.guid == "BOT"
-			pl.UserID = rp.userID
+			pl.Name = "unknown"
+			pl.IsUnknown = true
 		}
 	}
 	p.gameState.playersByEntityID[entityID] = pl
-	p.gameState.playersByUserID[rp.userID] = pl
+
+	if rp != nil {
+		p.gameState.playersByUserID[rp.userID] = pl
+	}
 
 	pl.EntityID = entityID
 	pl.Entity = playerEntity

game_events.go

@@ -282,6 +282,11 @@ func (geh gameEventHandler) weaponFire(data map[string]*msg.CSVCMsg_GameEventKey
 
 func (geh gameEventHandler) weaponReload(data map[string]*msg.CSVCMsg_GameEventKeyT) {
 	pl := geh.playerByUserID32(data["userid"].GetValShort())
+	if pl == nil {
+		// see #162, "unknown" players since November 2019 update
+		return
+	}
+
 	pl.IsReloading = true
 	geh.dispatch(events.WeaponReload{
 		Player: pl,

parser.go

@@ -280,6 +280,7 @@ func (p demoInfoProvider) IngameTick() int {
 }
 
 func (p demoInfoProvider) TickRate() float64 {
+	// TODO: read tickRate from CVARs as fallback
 	return p.parser.header.TickRate()
 }