fix: validate To BCD scheme option

src/core/operations/ToBCD.mjs

@@ -67,6 +67,10 @@ class ToBCD extends Operation {
             signed = args[2],
             outputFormat = args[3];
 
+        if (!encoding) {
+            throw new OperationError("Invalid BCD encoding scheme");
+        }
+
         // Split input number up into separate digits
         const digits = input.toFixed().split("");
 

tests/operations/tests/BCD.mjs

@@ -52,6 +52,17 @@ TestRegister.addTests([
             }
         ]
     },
+    {
+        name: "To BCD: invalid scheme",
+        input: "43",
+        expectedOutput: "Invalid BCD encoding scheme",
+        recipeConfig: [
+            {
+                "op": "To BCD",
+                "args": ["", true, false, "Nibbles"]
+            }
+        ]
+    },
     {
         name: "From BCD: default 0",
         input: "0000",