Validate View Bit Plane colour input

src/core/operations/ViewBitPlane.mjs

@@ -59,6 +59,12 @@ class ViewBitPlane extends Operation {
             colourIndex = COLOUR_OPTIONS.indexOf(colour),
             bitIndex = 7 - bit;
 
+        if (colourIndex === -1) {
+            throw new OperationError(
+                `Error: Colour argument must be one of ${COLOUR_OPTIONS.join(", ")}`,
+            );
+        }
+
         if (bit < 0 || bit > 7) {
             throw new OperationError(
                 "Error: Bit argument must be between 0 and 7",

tests/operations/tests/Image.mjs

@@ -230,6 +230,21 @@ TestRegister.addTests([
             }
         ]
     },
+    {
+        name: "View Bit Plane: invalid colour",
+        input: PNG_HEX,
+        expectedOutput: "Error: Colour argument must be one of Red, Green, Blue, Alpha",
+        recipeConfig: [
+            {
+                op: "From Hex",
+                args: ["None"]
+            },
+            {
+                op: "View Bit Plane",
+                args: ["", 7]
+            },
+        ],
+    },
     {
         name: "Randomize Colour Palette",
         "input": PNG_HEX,