Use Color type instead of string for custom color scales

Author: kMutagene

src/Plotly.NET/CommonAbstractions/StyleParams.fs

@@ -716,7 +716,7 @@ module StyleParam =
     /// The colorscale must be a collection containing a mapping of a normalized value (between 0.0 and 1.0) to it's color. At minimum, a mapping for the lowest (0.0) and highest (1.0) values are required.
     [<RequireQualifiedAccess>]
     type Colorscale =
-        | Custom of seq<float * string>
+        | Custom of seq<float * Color>
         | RdBu
         | Earth
         | Blackbody
@@ -733,9 +733,15 @@ module StyleParam =
         | Rainbow
         | Viridis
         | Cividis
+
         static member convert =
             function
-            | Custom (cScale) -> cScale |> Seq.map (fun (v, color) -> [| box v; box color |]) |> Array.ofSeq |> box
+            | Custom (cScale) ->
+                if Seq.length cScale < 2 then
+                    failwith
+                        "Color scale did not contain enough values. At minimum, a mapping for the lowest (0.0) and highest (1.0) values are required"
+
+                cScale |> Seq.map (fun (v, color) -> [| box v; box color |]) |> Array.ofSeq |> box
             | RdBu -> box "RdBu"
             | Earth -> box "Earth"
             | Blackbody -> box "Blackbody"

src/Plotly.NET/Plotly.NET.fsproj

@@ -35,9 +35,9 @@
     <None Include="..\..\docs\img\logo.png" Pack="true" PackagePath="\" />
     <Compile Include="AssemblyInfo.fs" />
     <Compile Include="InternalUtils.fs" />
-    <Compile Include="CommonAbstractions\StyleParams.fs" />
     <Compile Include="CommonAbstractions\ColorKeyword.fs" />
     <Compile Include="CommonAbstractions\Colors.fs" />
+    <Compile Include="CommonAbstractions\StyleParams.fs" />
     <Compile Include="CommonAbstractions\TickFormatStop.fs" />
     <Compile Include="CommonAbstractions\Frame.fs" />
     <Compile Include="CommonAbstractions\Font.fs" />