Move .isEmpty to $isEmpty (#5424)

* Move .isEmpty to $isEmpty

* Adjust usages

packages/api-derive/src/balances/account.ts

@@ -116,7 +116,7 @@ function querySystemAccount (api: DeriveApi, accountId: AccountId): Observable<R
 
       const nonce = (infoOrTuple as AccountInfo).nonce || (infoOrTuple as [Index, AccountData])[0];
 
-      if (!data || data.isEmpty) {
+      if (!data || data.$isEmpty) {
         return [
           nonce,
           [[zeroBalance(api), zeroBalance(api), zeroBalance(api), zeroBalance(api)]]

packages/api-derive/src/democracy/proposals.ts

@@ -30,7 +30,7 @@ function isNewDepositors (depositors: ITuple<[Vec<AccountId>, Balance]> | ITuple
 function parse ([proposals, images, optDepositors]: Result): DeriveProposal[] {
   return proposals
     .filter(([, , proposer], index): boolean =>
-      !!(optDepositors[index]?.isSome) && !proposer.isEmpty
+      !!(optDepositors[index]?.isSome) && !proposer.$isEmpty
     )
     .map(([index, hash, proposer], proposalIndex): DeriveProposal => {
       const depositors = optDepositors[proposalIndex].unwrap();

packages/api-derive/src/imOnline/receivedHeartbeats.ts

@@ -19,7 +19,7 @@ function mapResult ([result, validators, heartbeats, numBlocks]: [DeriveHeartbea
   validators.forEach((validator, index): void => {
     const validatorId = validator.toString();
     const blockCount = numBlocks[index];
-    const hasMessage = !heartbeats[index].isEmpty;
+    const hasMessage = !heartbeats[index].$isEmpty;
     const prev = result[validatorId];
 
     if (!prev || prev.hasMessage !== hasMessage || !prev.blockCount.eq(blockCount)) {

packages/api-derive/src/tx/signingInfo.ts

@@ -37,7 +37,7 @@ function signingHeader (api: DeriveApi): Observable<Header> {
       switchMap((header) =>
         // check for chains at genesis (until block 1 is produced, e.g. 6s), since
         // we do need to allow transactions at chain start (also dev/seal chains)
-        header.parentHash.isEmpty
+        header.parentHash.$isEmpty
           ? of(header)
           // in the case of the current block, we use the parent to minimize the
           // impact of forks on the system, but not completely remove it