Stop silent fallback when unknown canvas / colormap

Author: kojix2

spec/unicode_plot_spec.cr

@@ -49,6 +49,12 @@ describe UnicodePlot do
       end
     end
 
+    it "raises on unknown canvas" do
+      expect_raises(ArgumentError, /unknown canvas: mystery/) do
+        UnicodePlot.lineplot([1.0, 2.0], [1.0, 4.0], canvas: :mystery)
+      end
+    end
+
     it "accepts RGB tuple color" do
       p = UnicodePlot.lineplot([1.0, 2.0], [1.0, 2.0], color: {0, 0, 255})
       p.to_s.should be_a(String)
@@ -375,6 +381,12 @@ describe UnicodePlot do
       p = UnicodePlot.heatmap([[1_i128, 2_i128], [3_i128, 4_i128]])
       p.to_s.should be_a(String)
     end
+
+    it "raises on unknown colormap" do
+      expect_raises(ArgumentError, /unknown colormap: mystery/) do
+        UnicodePlot.heatmap([[1.0, 2.0], [3.0, 4.0]], colormap: :mystery)
+      end
+    end
   end
 
   describe "stairs" do

src/unicode_plot/graphics/heatmap_graphics.cr

@@ -33,7 +33,7 @@ module UnicodePlot
   }
 
   def colormap_callback(name : Symbol) : Proc(Float64, Float64, Float64, UInt32)
-    stops = COLORMAP_STOPS[name]? || COLORMAP_STOPS[:viridis]
+    stops = COLORMAP_STOPS[name]? || raise ArgumentError.new("unknown colormap: #{name}")
     ->(z : Float64, zmin : Float64, zmax : Float64) {
       return INVALID_COLOR unless z.finite?
       t = zmax > zmin ? ((z - zmin) / (zmax - zmin)).clamp(0.0, 1.0) : 0.5

src/unicode_plot/plot.cr

@@ -267,11 +267,8 @@ module UnicodePlot
             yflip: yflip, xflip: xflip,
             yscale: yscale.is_a?(Symbol) ? yscale.as(Symbol) : yscale.as(Proc(Float64, Float64)),
             xscale: xscale.is_a?(Symbol) ? xscale.as(Symbol) : xscale.as(Proc(Float64, Float64)))
-          else BrailleCanvas.new(h, w,
-            origin_y: my, origin_x: mx,
-            height: by - my, width: bx - mx,
-            blend: blend, visible: (w >= 0),
-            yflip: yflip, xflip: xflip)
+          else
+            raise ArgumentError.new("unknown canvas: #{canvas_type}")
           end
 
     plot = Plot.new(can,