Throw a better error when facet: "exclude" is used without faceting?

[mbostock]

This current throws TypeError: Cannot read properties of undefined (reading 'facetsIndex').

Plot.plot({
  marks: [
    Plot.dot(penguins, {x: "culmen_depth_mm", y: "culmen_length_mm", fill: "#ccc", facet: "exclude"}),
    Plot.dot(penguins, {x: "culmen_depth_mm", y: "culmen_length_mm", fx: "sex", fy: "species"})
  ]
})

Since no top-level or mark-level faceting is declared, facet: "exclude" should probably throw a specific helpful error instead of crashing internally.