fix: fix mcping when no favicon throw exception

src/main/kotlin/cn/rtast/fancybot/commands/MCPingCommand.kt

@@ -45,17 +45,14 @@ class MCPingCommand : BaseCommand() {
         try {
             val rawResponse = pingInstance.pingServer(host, port)
             val jsonResponse = rawResponse?.fromJson<MCPingResponse>()!!
-            val msg = MessageChain.Builder()
-                .addAt(message.sender.userId)
-                .addNewLine()
-                .addImage(jsonResponse.favicon, true)
-                .addText("服务器地址: $host:$port")
-                .addNewLine()
-                .addText("协议版本号: ${jsonResponse.version.protocol}/${jsonResponse.version.name}")
-                .addNewLine()
-                .addText("玩家: ${jsonResponse.players.online}/${jsonResponse.players.max}")
-                .build()
-            listener.sendGroupMessage(message.groupId, msg)
+            val msg = MessageChain.Builder().addAt(message.sender.userId).addNewLine()
+            if (jsonResponse.favicon != null) msg.addImage(jsonResponse.favicon, true)
+            msg.addText("服务器地址: $host:$port")
+            msg.addNewLine()
+            msg.addText("协议版本号: ${jsonResponse.version.protocol}/${jsonResponse.version.name}")
+            msg.addNewLine()
+            msg.addText("玩家: ${jsonResponse.players.online}/${jsonResponse.players.max}")
+            listener.sendGroupMessage(message.groupId, msg.build())
         } catch (_: Exception) {
             val msg = MessageChain.Builder()
                 .addAt(message.sender.userId)