*Make bls export an async wrapper to prevent top-level await

src/getImplementation.ts

@@ -6,7 +6,7 @@ const isNode = Object.prototype.toString.call(typeof process !== "undefined" ? p
 export async function getImplementation(impl: Implementation = "herumi"): Promise<IBls> {
   switch (impl) {
     case "herumi": {
-      return (await import("./herumi/index.js")).bls;
+      return await (await import("./herumi/index.js")).bls();
     }
 
     case "blst-native":

src/herumi/index.ts

@@ -5,19 +5,19 @@ import {init, destroy} from "./context.js";
 import {IBls} from "../types.js";
 import {functionalInterfaceFactory} from "../functional.js";
 
-await init();
-
 export * from "../constants.js";
 
 export {SecretKey, PublicKey, Signature, init, destroy};
 
-export const bls: IBls = {
+export const bls = async (): Promise<IBls> => {
+  await init();
+  return {
     implementation: "herumi",
     SecretKey,
     PublicKey,
     Signature,
 
     ...functionalInterfaceFactory({SecretKey, PublicKey, Signature}),
+  };
 };
-
 export default bls;