Validation of mapped aesthetics

[teunbrand]

This sort of works as intended, in that we see an error for an invalid aesthetic via SETTING.

VISUALISE bill_dep AS x, bill_len AS y FROM ggsql:penguins
  DRAW polygon SETTING linewidth => 20
#> Failed to execute query: Validation error: Layer 1: Invalid setting 'linewidth' for geom 'point'. 
#> Valid settings are: x, y, fill, stroke, size, shape, opacity

But this executes just fine:

VISUALISE bill_dep AS x, bill_len AS y FROM ggsql:penguins
  DRAW point MAPPING bill_len AS linewidth

And indeed uses a thicker line to draw points with higher bill_len, confirming the mapping works. Separately from the concern wether points should have a linewidth aesthetic, I think this at least suggests we should validate the layer mapping as well.