message: fix StructureSelectionControls.focus for single element
diff: @@ -46,8 +46,8 @@ export class StructureSelectionControls<P, S extends StructureSelectionControlsS
  focus = () => {
  const { extraRadius, minRadius, durationMs } = this.state
  + if (this.plugin.helpers.structureSelectionManager.stats.elementCount === 0) return
  const { sphere } = this.plugin.helpers.structureSelectionManager.getBoundary();
  - if (sphere.radius === 0) return
  const radius = Math.max(sphere.radius + extraRadius, minRadius);
  this.plugin.canvas3d.camera.focus(sphere.center, radius, durationMs);
  }
  