null on WASM non-available (#317)

packages/util-crypto/src/schnorrkel/ready.spec.ts

@@ -0,0 +1,25 @@
+// Copyright 2017-2019 @polkadot/util-crypto authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+describe('ready', () => {
+  let globalWA: typeof WebAssembly;
+
+  beforeEach(() => {
+    globalWA = (global as any).WebAssembly;
+    (global as any).WebAssembly = null;
+  });
+
+  afterEach(() => {
+    (global as any).WebAssembly = globalWA;
+  });
+
+  it('returns false when Webassembly is not available', async () => {
+    (global as any).WebAssembly = null;
+
+    const schnorrkelWaitReady = require('./ready').default;
+    const isReady = await schnorrkelWaitReady();
+
+    expect(isReady).toBe(false);
+  });
+});

packages/util-crypto/src/schnorrkel/schnorrkel-js/schnorrkel_js.js

@@ -255,9 +255,9 @@ wasmImports.__wbindgen_jsval_eq = function(a, b) {
 
 const createPromise = require('./schnorrkel_js_bg');
 
-const wasmPromise = createPromise(wasmImports);
+const wasmPromise = createPromise(wasmImports).catch(() => null);
 
 module.exports.isReady = function () { return !!wasm; }
 module.exports.waitReady = function () { return wasmPromise.then(() => !!wasm); }
 
-wasmPromise.then((_wasm) => { wasm = _wasm }).catch(() => {});
+wasmPromise.then((_wasm) => { wasm = _wasm });

packages/util-crypto/src/schnorrkel/schnorrkel-js/schnorrkel_js_bg.js

@@ -6,7 +6,15 @@ module.exports = async function createExportPromise (wasmImports) {
     './schnorrkel_js': wasmImports
   };
 
-  return WebAssembly
-    .instantiate(bytes, imports)
-    .then((wasm) => wasm.instance.exports);
+  if (!WebAssembly) {
+    return null;
+  }
+
+  try {
+    const { instance } = await WebAssembly.instantiate(bytes, imports);
+
+    return instance.exports;
+  } catch (error) {
+    return null;
+  }
 }