Fix buffer

Author: Isaac

submodules/TelegramApi/Sources/Buffer.swift

@@ -363,13 +363,16 @@ public class BufferReader {
         if count == 0 {
             return 0
         }
-        else if count > 0 && count <= 4 || self.offset + UInt(count) <= self.buffer._size {
-            var value: Int32 = 0
-            memcpy(&value, self.buffer.data?.advanced(by: Int(self.offset)), count)
-            self.offset += UInt(count)
-            return value
+        guard count > 0, count <= 4, self.offset + UInt(count) <= self.buffer._size else {
+            return nil
         }
-        return nil
+        guard let bufferData = self.buffer.data else {
+            return nil
+        }
+        var value: Int32 = 0
+        memcpy(&value, bufferData.advanced(by: Int(self.offset)), count)
+        self.offset += UInt(count)
+        return value
     }
 
     public func readBuffer(_ count: Int) -> Buffer? {