fix: handle empty generate image mode

src/core/operations/GenerateImage.mjs

@@ -76,6 +76,10 @@ class GenerateImage extends Operation {
 
         const bytesPerPixel = bytePerPixelMap[mode];
 
+        if (bytesPerPixel === undefined) {
+            throw new OperationError(`Unsupported Mode: (${mode})`);
+        }
+
         if (bytesPerPixel > 0 && input.length % bytesPerPixel !== 0) {
             throw new OperationError(
                 `Number of bytes is not a divisor of ${bytesPerPixel}`,

tests/operations/tests/Image.mjs

@@ -45,6 +45,17 @@ TestRegister.addTests([
             { op: "Render Image", args: ["Base64"] }
         ]
     },
+    {
+        name: "Generate Image: empty mode",
+        input: "",
+        expectedOutput: "Unsupported Mode: ()",
+        recipeConfig: [
+            {
+                op: "Generate Image",
+                args: ["", 8, 64]
+            }
+        ]
+    },
     {
         name: "Extract EXIF: nothing",
         input: "",