Some minor cleanups (#1966)

* Some minor cleanups

* Small additions

* Cleanup ExtrinsicEra decoding

* Minor adjustments

* Remove support for metadata v0 parsing

* Adjust refCountDelay

* refCountDelay comments

* Adjust Metadata tests

* Metadata default creation

* Funky lines

* Cleanup as AccountIdAndIndex

* Some derive returns

* Try and cleanup info extraction

packages/api-derive/src/chain/bestNumber.ts

@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { BlockNumber, Header } from '@polkadot/types/interfaces';
+import { BlockNumber } from '@polkadot/types/interfaces';
 
 import { Observable } from 'rxjs';
 import { map } from 'rxjs/operators';
@@ -25,6 +25,6 @@ import { memo } from '../util';
 export function bestNumber (api: ApiInterfaceRx): () => Observable<BlockNumber> {
   return memo((): Observable<BlockNumber> =>
     api.derive.chain.subscribeNewHeads().pipe(
-      map((header: Header): BlockNumber => header.number.unwrap())
+      map((header) => header.number.unwrap())
     ));
 }

packages/api-derive/src/chain/bestNumberFinalized.ts

@@ -26,6 +26,6 @@ import { memo } from '../util';
 export function bestNumberFinalized (api: ApiInterfaceRx): () => Observable<BlockNumber> {
   return memo((): Observable<BlockNumber> =>
     api.rpc.chain.subscribeFinalizedHeads().pipe(
-      map((header): BlockNumber => header.number.unwrap())
+      map((header) => header.number.unwrap())
     ));
 }

packages/api-derive/src/chain/getHeader.ts

@@ -2,14 +2,11 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { AccountId } from '@polkadot/types/interfaces';
 import { ApiInterfaceRx } from '@polkadot/api/types';
 
 import { Observable, combineLatest, of } from 'rxjs';
 import { catchError, map } from 'rxjs/operators';
 
-import { Vec } from '@polkadot/types';
-
 import { HeaderExtended } from '../type';
 import { memo } from '../util';
 
@@ -32,7 +29,7 @@ export function getHeader (api: ApiInterfaceRx): (hash: Uint8Array | string) =>
     combineLatest([
       api.rpc.chain.getHeader(hash),
       api.query.session
-        ? api.query.session.validators.at(hash) as Observable<Vec<AccountId>>
+        ? api.query.session.validators.at(hash)
         : of([])
     ]).pipe(
       map(([header, validators]): HeaderExtended =>