Handle plain multi queries diguised as map-form (#4011)

Author: jacogr

packages/api/src/base/Decorate.ts

@@ -373,9 +373,11 @@ export abstract class Decorate<ApiType extends ApiTypes> extends Events {
         : this._rpcCore.state.queryStorageAt)(
         calls.map((args: QueryableStorageMultiArg<ApiType>) =>
           Array.isArray(args)
-            ? args[0].creator.meta.type.asMap.hashers.length === 1
-              ? [args[0].creator, args.slice(1)]
-              : [args[0].creator, ...args.slice(1)]
+            ? args[0].creator.meta.type.isPlain
+              ? [args[0].creator]
+              : args[0].creator.meta.type.asMap.hashers.length === 1
+                ? [args[0].creator, args.slice(1)]
+                : [args[0].creator, ...args.slice(1)]
             : [args.creator])));
   }
 

packages/types/src/primitive/StorageKey.ts

@@ -51,7 +51,7 @@ export function unwrapStorageType (registry: Registry, type: StorageEntryTypeLat
 }
 
 /** @internal */
-function decodeStorageKey (registry: Registry, value?: string | Uint8Array | StorageKey | StorageEntry | [StorageEntry, unknown[]?]): Decoded {
+function decodeStorageKey (value?: string | Uint8Array | StorageKey | StorageEntry | [StorageEntry, unknown[]?]): Decoded {
   // eslint-disable-next-line @typescript-eslint/no-use-before-define
   if (value instanceof StorageKey) {
     return {
@@ -174,7 +174,7 @@ export class StorageKey<A extends AnyTuple = AnyTuple> extends Bytes implements
   private _section?: string;
 
   constructor (registry: Registry, value?: string | Uint8Array | StorageKey | StorageEntry | [StorageEntry, unknown[]?], override: Partial<StorageKeyExtra> = {}) {
-    const { key, method, section } = decodeStorageKey(registry, value);
+    const { key, method, section } = decodeStorageKey(value);
 
     super(registry, key);