message: Minor improvement to Vulkan robustness.
diff: @@ -1639,7 +1639,15 @@ void VulkanDriver::draw(PipelineState pipelineState, Handle<HwRenderPrimitive> r
  attrib = prim.vertexBuffer->attributes[0];
  }
  - buffers[attribIndex] = prim.vertexBuffer->buffers[attrib.buffer]->getGpuBuffer();
  + const VulkanBuffer* buffer = prim.vertexBuffer->buffers[attrib.buffer];
  +
  + // If the vertex buffer is missing a constituent buffer object, skip the draw call.
  + // There is no need to emit an error message because this is not explicitly forbidden.
  + if (buffer == nullptr) {
  + return;
  + }
  +
  + buffers[attribIndex] = buffer->getGpuBuffer();
  offsets[attribIndex] = attrib.offset;
  varray.attributes[attribIndex] = {
  .location = attribIndex, // matches the GLSL layout specifier
  