Correct handling for storage Option<Option<Type>> (#4927)

* Correct handling for storage Option<Option<Type>>

* Adjust

packages/types-codec/src/base/Option.spec.ts

@@ -43,6 +43,24 @@ describe('Option', (): void => {
     });
   });
 
+  it('can decode a nested Option', (): void => {
+    expect(
+      new Option(
+        registry,
+        Option.with(Option.with(Text)),
+        new Option(
+          registry,
+          Option.with(Text),
+          new Option(
+            registry,
+            Text,
+            new Uint8Array([1, 3 << 2, 66, 67, 68])
+          )
+        )
+      ).toU8a()
+    ).toEqual(new Uint8Array([1, 1, 1, 3 << 2, 66, 67, 68]));
+  });
+
   it('can convert between different Some/None', (): void => {
     const def = '{ "foo":"Text", "zar":"Text" }';
     const none = new Option(registry, def, null);

packages/types-codec/src/base/Option.ts

@@ -29,16 +29,23 @@ class None extends Null {
 
 /** @internal */
 function decodeOption (registry: Registry, Type: CodecClass, value?: unknown): Codec {
-  // In the case of an option, unwrap the inner
-  if (value instanceof Option) {
-    value = value.value;
-  }
-
-  if (isNull(value) || isUndefined(value) || value === '0x' || value instanceof None) {
-    return new None(registry);
-  } else if (value instanceof Type) {
+  if (value instanceof Type) {
     // don't re-create, use as it (which also caters for derived types)
     return value;
+  } else if (value instanceof Option) {
+    if (value.value instanceof Type) {
+      // same instance, return it
+      return value.value;
+    } else if (value.isNone) {
+      // internal is None, we are also none
+      return new None(registry);
+    }
+
+    // convert the actual value into known
+    return new Type(registry, value.value);
+  } else if (isNull(value) || isUndefined(value) || value === '0x' || value instanceof None) {
+    // anyhting empty we pass as-is
+    return new None(registry);
   } else if (isU8a(value)) {
     // the isU8a check happens last in the if-tree - since the wrapped value
     // may be an instance of it, so Type and Option checks go in first