message: add a type assertion
diff: @@ -272,7 +272,7 @@ function setupWebSocket() {
  document.querySelector('html').style.filter = `invert(${data.invert * 100}%)`
  document.querySelector('html').style.background = 'white'
  }
  - document.querySelector('#viewerContainer').style.background = data.bgColor
  + (document.querySelector('#viewerContainer') as HTMLElement).style.background = data.bgColor
  if (data.keybindings) {
  reverseSynctexKeybinding = data.keybindings['synctex']
  registerSynctexKeybinding(reverseSynctexKeybinding)
  