Fix AUDIO_WORKLET + MODULARIZE

The change that was made back in #21775 means that its no longer OK to
ignore the return value of the `MODULARIZE` constructor function.

Fixes: #21908

src/audio_worklet.js

@@ -161,7 +161,7 @@ class BootstrapMessages extends AudioWorkletProcessor {
         // MODULARIZE+AUDIO_WORKLET builds.
         if (globalThis.AudioWorkletModule) {
           // This populates the Module object with all the Wasm properties
-          AudioWorkletModule(Module);
+          globalThis.Module = await AudioWorkletModule(Module);
           // We have now instantiated the Module function, can discard it from
           // global scope
           delete globalThis.AudioWorkletModule;