Ignore value of __proxy in WASM_WORKERS mode. NFC

Fixes: #20134

Author: sbc100

src/jsifier.js

@@ -228,11 +228,11 @@ function(${args}) {
     if (SHARED_MEMORY) {
       const proxyingMode = LibraryManager.library[symbol + '__proxy'];
       if (proxyingMode) {
-        if (proxyingMode !== 'sync' && proxyingMode !== 'async') {
-          throw new Error(`Invalid proxyingMode ${symbol}__proxy: '${proxyingMode}' specified!`);
-        }
-        const sync = proxyingMode === 'sync';
         if (PTHREADS) {
+          if (proxyingMode !== 'sync' && proxyingMode !== 'async') {
+            error(`Invalid proxyingMode ${symbol}__proxy: '${proxyingMode}' specified!`);
+          }
+          const sync = proxyingMode === 'sync';
           snippet = modifyJSFunction(snippet, (args, body, async_, oneliner) => {
             if (oneliner) {
               body = `return ${body}`;

test/wasm_worker/proxied_function.c

@@ -28,8 +28,10 @@ void run_in_worker()
   }
 }
 
-int main()
-{
+int main() {
+  // Calling the proxied function form the main thread should succeed.
+  proxied_js_function();
+
+  // Calling it from a worker should fail
   emscripten_wasm_worker_post_function_v(emscripten_malloc_wasm_worker(1024), run_in_worker);
-  proxied_js_function(); // Pin a dependency from C code to the JS function to avoid needing to mess with cmdline export directives
 }

test/wasm_worker/proxied_function.js

@@ -1,7 +1,9 @@
 addToLibrary({
-  proxied_js_function__proxy: 'sync',
+  // Use a non-standaed __proxy flag here.
+  // This is used, for example, in library_html5_webgl.js. With WASM_WORKERS
+  // we want the build to succeed rather than complain about the invalid
+  // proxy type.
+  proxied_js_function__proxy: 'sync_on_webgl_context_handle_thread',
   proxied_js_function__sig: 'v',
-  proxied_js_function: function() {
-  	console.log('In proxied_js_function');
-  }
+  proxied_js_function: () => console.log('In proxied_js_function'),
 });