Fix glfw usage of callUserCallback and add checks around it

Supersedes #17438 and #17376.

Author: sbc100

src/library.js

@@ -3500,6 +3500,10 @@ mergeInto(LibraryManager.library, {
       return;
     }
     try {
+#if ASSERTIONS
+      assert(!inUserCode, 'callUserCallback called when already running user code');
+      inUserCode = true;
+#endif
       func();
 #if EXIT_RUNTIME || USE_PTHREADS
 #if USE_PTHREADS && !EXIT_RUNTIME
@@ -3510,6 +3514,9 @@ mergeInto(LibraryManager.library, {
     } catch (e) {
       handleException(e);
     }
+#if ASSERTIONS
+    inUserCode = false;
+#endif
   },
 
   $maybeExit__deps: ['exit', '$handleException',

src/library_glfw.js

@@ -80,7 +80,6 @@ var LibraryGLFW = {
     },
 
   $GLFW__deps: ['emscripten_get_now', '$GL', '$Browser', '$GLFW_Window',
-    '$callUserCallback',
     '$allocateUTF8',
 #if FILESYSTEM
     '$FS',
@@ -591,27 +590,23 @@ var LibraryGLFW = {
 
       if (!GLFW.active.windowSizeFunc) return;
 
-      callUserCallback(function() {
 #if USE_GLFW == 2
-        {{{ makeDynCall('vii', 'GLFW.active.windowSizeFunc') }}}(GLFW.active.width, GLFW.active.height);
+      {{{ makeDynCall('vii', 'GLFW.active.windowSizeFunc') }}}(GLFW.active.width, GLFW.active.height);
 #endif
 
 #if USE_GLFW == 3
-        {{{ makeDynCall('viii', 'GLFW.active.windowSizeFunc') }}}(GLFW.active.id, GLFW.active.width, GLFW.active.height);
+      {{{ makeDynCall('viii', 'GLFW.active.windowSizeFunc') }}}(GLFW.active.id, GLFW.active.width, GLFW.active.height);
 #endif
-      });
     },
 
     onFramebufferSizeChanged: function() {
       if (!GLFW.active) return;
 
       if (!GLFW.active.framebufferSizeFunc) return;
 
-      callUserCallback(function() {
 #if USE_GLFW == 3
-        {{{ makeDynCall('viii', 'GLFW.active.framebufferSizeFunc') }}}(GLFW.active.id, GLFW.active.width, GLFW.active.height);
+      {{{ makeDynCall('viii', 'GLFW.active.framebufferSizeFunc') }}}(GLFW.active.id, GLFW.active.width, GLFW.active.height);
 #endif
-      });
     },
 
     getTime: function() {
@@ -1132,7 +1127,7 @@ var LibraryGLFW = {
     Module["canvas"].addEventListener('drop', GLFW.onDrop, true);
     Module["canvas"].addEventListener('dragover', GLFW.onDragover, true);
 
-    Browser.resizeListeners.push(function(width, height) {
+    Browser.resizeListeners.push((width, height) => {
        GLFW.onCanvasResize(width, height);
     });
     return 1; // GL_TRUE

src/postamble.js

@@ -161,6 +161,9 @@ function callMain(args) {
     abortWrapperDepth += 2;
 #endif
 
+#if ASSERTIONS
+    inUserCode = true;
+#endif
 #if STANDALONE_WASM
     entryFunction();
     // _start (in crt1.c) will call exit() if main return non-zero.  So we know
@@ -189,6 +192,9 @@ function callMain(args) {
     return handleException(e);
 #endif // !PROXY_TO_PTHREAD
   } finally {
+#if ASSERTIONS
+    inUserCode = false;
+#endif
     calledMain = true;
 
 #if ABORT_ON_WASM_EXCEPTIONS

src/preamble.js

@@ -368,6 +368,7 @@ var runDependencyWatcher = null;
 var dependenciesFulfilled = null; // overridden to take different actions when all run dependencies are fulfilled
 #if ASSERTIONS
 var runDependencyTracking = {};
+var inUserCode = false;
 #endif
 
 function getUniqueRunDependency(id) {