message: Avoid crash when fetching vs out with expected index buffer unbound
  * This is clearly invalid but it's trivial to protect against a divide by 0
  which we do on other APIs, so we do that here.
diff: @@ -1642,6 +1642,8 @@ void VulkanReplay::FetchVSOut(uint32_t eventId, VulkanRenderState &state)
  }
  uint32_t idxsize = state.ibuffer.bytewidth;
  + if(idxsize == 0)
  + idxsize = 4U;
  uint32_t maxIndex = RDCMAX(action->baseVertex, 0) + numVerts - 1;
  