DataInspector: fix an attribute extraction bug for heatmaps & images

If the colorrange attribute is left at default it returns
MakieCore.Automatic; the method for `get` that was called at
show_imagelike does not check for this type so the ensuing call to
interpolated_getindex would fail.

The colorrange is now generically extracted and
calculated_colors[].colorrange[] is preferred as it contains the actual
range.

Fixes #3101

src/interaction/inspector.jl

@@ -662,7 +662,7 @@ function show_imagelike(inspector, plot, name, edge_based)
     a._color[] = if z isa AbstractFloat
         interpolated_getindex(
             to_colormap(plot.colormap[]), z,
-            to_value(get(plot.attributes, :colorrange, (0, 1)))
+            extract_colorrange(plot)
         )
     else
         z

src/makielayout/blocks/colorbar.jl

@@ -25,6 +25,16 @@ function colorbar_check(keys, kwargs_keys)
     end
 end
 
+function extract_colorrange(@nospecialize(plot::AbstractPlot))::Vec2{Float64}
+    if haskey(plot, :calculated_colors) && plot.calculated_colors[] isa Makie.ColorMapping
+        return plot.calculated_colors[].colorrange[]
+    elseif haskey(plot, :colorrange) && !(plot.colorrange[] isa Makie.Automatic)
+        return plot.colorrange[]
+    else
+        error("colorrange not found and calculated_colors for the plot is missing or is not a proper color map. Heatmaps and images should always contain calculated_colors[].colorrange")
+    end
+end
+
 function extract_colormap(@nospecialize(plot::AbstractPlot))
     has_colorrange = haskey(plot, :colorrange) && !(plot.colorrange[] isa Makie.Automatic)
     if haskey(plot, :calculated_colors) && plot.calculated_colors[] isa Makie.ColorMapping