Minor debugging improvements from esm-integration work. NFC (#24296)

Author: sbc100

src/lib/libbrowser.js

@@ -691,7 +691,8 @@ var LibraryBrowser = {
         var data = await readAsync(url, false);
         eval(data);
         loadDone();
-      } catch {
+      } catch (e) {
+        err(e);
         loadError();
       }
       return;

src/lib/libstack_trace.js

@@ -105,7 +105,7 @@ var LibraryStackTrace = {
     abort('Cannot use convertFrameToPC (needed by __builtin_return_address) without -sUSE_OFFSET_CONVERTER');
 #else
 #if ASSERTIONS
-    assert(wasmOffsetConverter);
+    assert(wasmOffsetConverter, 'wasmOffsetConverter global not found');
 #endif
     var match;
 

test/core/test_asyncify_assertions.c

@@ -3,19 +3,16 @@
 
 EM_JS(void, suspend, (), {
   Asyncify.handleSleep((wakeUp) => {
-    Module.resume = wakeUp;
-    setTimeout(function() {
-      Module._resume_from_inside_c();
-    }, 1);
+    Module.doResume = wakeUp;
+    setTimeout(() => _resume_from_inside_c(), 1);
   });
 });
 
 EM_JS(void, resume, (), {
-  Module.resume();
+  Module.doResume();
 });
 
-EMSCRIPTEN_KEEPALIVE
-void resume_from_inside_c() {
+EMSCRIPTEN_KEEPALIVE void resume_from_inside_c() {
   // A C function that then resumes. This C code will be on the stack as we
   // try to resume, but that is invalid - we need to start a resume from the
   // *outside* of the wasm module. An assertion should catch this.

test/test_emscripten_async_load_script.c

@@ -39,7 +39,8 @@ void load2() {
 }
 
 void error2() {
-  printf("fail2\n");
+  printf("failed to load second script\n");
+  assert(false);
 }
 
 void load1() {
@@ -49,7 +50,8 @@ void load1() {
 }
 
 void error1() {
-  printf("fail1\n");
+  printf("failed to load first script\n");
+  assert(false);
 }
 
 int main() {