Fix incompat with immedeately fast 1.1.25

Turns out uploading empty buffers isn't the best idea I've ever had,
but it also wasn't the worst one I ever had.

Maybe results in some performance gains even, who knows.

common/src/main/java/dev/schmarrn/lighty/event/BufferHolder.java

@@ -43,10 +43,15 @@ void upload(BufferBuilder.RenderedBuffer buffer) {
         if (vertexBuffer != null) {
             vertexBuffer.close();
         }
-        vertexBuffer = new VertexBuffer(VertexBuffer.Usage.DYNAMIC);
-        vertexBuffer.bind();
-        vertexBuffer.upload(buffer);
-        VertexBuffer.unbind();
+        if (buffer.isEmpty()) {
+            // Don't upload
+            vertexBuffer = null;
+        } else {
+            vertexBuffer = new VertexBuffer(VertexBuffer.Usage.DYNAMIC);
+            vertexBuffer.bind();
+            vertexBuffer.upload(buffer);
+            VertexBuffer.unbind();
+        }
     }
 
     void draw(Matrix4f positionMatrix, Matrix4f projectionMatrix, ShaderInstance shader) {