Add missing comment

src/contract_wrappers/contract_wrapper.ts

@@ -125,6 +125,7 @@ export class ContractWrapper {
     }
     private async _reconcileBlockAsync(): Promise<void> {
         const latestBlock = await this._web3Wrapper.getBlockAsync('latest');
+        // We need to coerce to Block type cause Web3.Block includes types for mempool bloks
         this._blockAndLogStreamer.reconcileNewBlock(latestBlock as any as Block);
     }
 }