Check {read,write}BufferSize are both zero or positive

Signed-off-by: Graham <gpe@openrs2.dev>

cache/src/main/java/dev/openrs2/cache/BufferedFileChannel.kt

@@ -24,6 +24,8 @@ public class BufferedFileChannel(
     private var writePos = -1L
 
     init {
+        require(readBufferSize >= 0 && writeBufferSize >= 0)
+
         val buf = alloc.buffer(readBufferSize, readBufferSize)
         try {
             writeBuffer = alloc.buffer(writeBufferSize, writeBufferSize)