Remove unnecessary rigmarole around importing the script as a blob (libretro#17642)

Author: JoeOsborn

Makefile.emscripten

@@ -118,7 +118,7 @@ ifeq ($(HAVE_WASMFS), 1)
 endif
 
 ifeq ($(PROXY_TO_PTHREAD),1)
-   LIBS += -sUSE_ES6_IMPORT_META=0 -sENVIRONMENT=worker,web
+   LIBS += -sENVIRONMENT=worker,web
    LIBS += -sPROXY_TO_PTHREAD -sOFFSCREENCANVAS_SUPPORT
    DEFINES += -DUSE_OFFSCREENCANVAS=1 -DPROXY_TO_PTHREAD=1
 else

frontend/drivers/platform_emscripten.c

@@ -461,6 +461,11 @@ static uint64_t frontend_emscripten_get_free_mem(void)
 }
 
 void emscripten_bootup_mainloop(void *argptr) {
+   if(retro_started) {
+      /* A stale extra call to bootup_mainloop for some reason */
+      RARCH_ERR("[Emscripten] unexpected second call to bootup_mainloop after rarch_main called\n");
+      return;
+   }
    if(filesystem_ready) {
       args_t *args = (args_t*)argptr;
       emscripten_cancel_main_loop();

pkg/emscripten/libretro-thread/libretro.js

@@ -216,24 +216,15 @@ $(function() {
    loadCore(core);
 });
 
-async function downloadScript(src) {
-  let resp = await fetch(src);
-  let blob = await resp.blob();
-  return blob;
-}
-
 function loadCore(core) {
    // Make the core the selected core in the UI.
    var coreTitle = $('#core-selector a[data-core="' + core + '"]').addClass('active').text();
    $('#dropdownMenu1').text(coreTitle);
-   downloadScript("./"+core+"_libretro.js").then(scriptBlob => {
-      Module.mainScriptUrlOrBlob = scriptBlob;
-      import(URL.createObjectURL(scriptBlob)).then(script => {
-         script.default(Module).then(mod => {
-            Module = mod;
-         }).catch(err => { console.error("Couldn't instantiate module",err); throw err; });
-      }).catch(err => { console.error("Couldn't load script",err); throw err; });
-   });
+   import("./"+core+"_libretro.js").then(script => {
+     script.default(Module).then(mod => {
+       Module = mod;
+     }).catch(err => { console.error("Couldn't instantiate module",err); throw err; });
+   }).catch(err => { console.error("Couldn't import module"); throw err; });
 }
 
 const setupWorker = new Worker("libretro.worker.js");