fix: resolve crashes on invalid script hot reload

include/Application.h

@@ -14,6 +14,7 @@ public:
 private:
     ScriptEngine scriptEngine;
     HotReload* hotReload;
+    bool scriptCompilationError;
     
     static const int WINDOW_WIDTH = 800;
     static const int WINDOW_HEIGHT = 600;

include/ScriptEngine.h

@@ -21,7 +21,10 @@ private:
     asIScriptEngine* engine;
     asIScriptFunction* updateFunc;
     asIScriptFunction* drawFunc;
+    asIScriptModule* currentModule;
+    bool hasValidScript;
 
     static void MessageCallback(const asSMessageInfo* msg, void* param);
     std::string ReadFile(const std::string& filename);
+    void ClearCachedFunctions();
 };

scripts/test.as

@@ -2,11 +2,10 @@ float x = 50;
 float y = 100;
 
 void Update(float dt) {
-    x += 50 * dt; // move text horizontally
+    x += 50 * dt;
     if (x > 800) x = 0;
 }
 
 void Draw() {
-    DrawText("Hello from AngelScript!", int(x), int(y), 20, 0xFF0000FF);
-
+    DrawText("Hello from AngelScript - Working perfectly!", int(x), int(y), 20, 0xFF0000FF);
 }

src/Application.cpp

@@ -7,7 +7,7 @@
 const char* Application::WINDOW_TITLE = "Raylib + AngelScript";
 const char* Application::SCRIPT_FILE = "scripts/test.as";
 
-Application::Application() : hotReload(nullptr) {
+Application::Application() : hotReload(nullptr), scriptCompilationError(false) {
 }
 
 Application::~Application() {
@@ -29,7 +29,7 @@ bool Application::Initialize() {
     hotReload = new HotReload(SCRIPT_FILE);
 
     // Compile initial script
-    scriptEngine.CompileScript(SCRIPT_FILE);
+    scriptCompilationError = !scriptEngine.CompileScript(SCRIPT_FILE);
 
     return true;
 }
@@ -49,7 +49,11 @@ void Application::Run() {
 void Application::Update(float deltaTime) {
     // Check for hot reload
     if (hotReload && hotReload->CheckForChanges()) {
-        scriptEngine.CompileScript(SCRIPT_FILE);
+        bool success = scriptEngine.CompileScript(SCRIPT_FILE);
+        scriptCompilationError = !success;
+        if (!success) {
+            std::cout << "Script compilation failed - keeping previous version\n";
+        }
     }
 
     // Call script Update function
@@ -60,7 +64,12 @@ void Application::Draw() {
     BeginDrawing();
     ClearBackground(RAYWHITE);
 
-    DrawText("Modify scripts/test.as to hot-reload!", 50, 50, 20, DARKGRAY);
+    // Show script error status in top left if there's an error, otherwise show normal message
+    if (scriptCompilationError) {
+        DrawText("SCRIPT ERROR - Check console for details", 10, 10, 16, RED);
+    } else {
+        DrawText("Modify scripts/test.as to hot-reload!", 50, 50, 20, DARKGRAY);
+    }
 
     // Call script Draw function
     scriptEngine.CallScriptFunction(scriptEngine.GetDrawFunction());

src/ScriptEngine.cpp

@@ -6,7 +6,7 @@
 #include <sstream>
 #include <assert.h>
 
-ScriptEngine::ScriptEngine() : engine(nullptr), updateFunc(nullptr), drawFunc(nullptr) {
+ScriptEngine::ScriptEngine() : engine(nullptr), updateFunc(nullptr), drawFunc(nullptr), currentModule(nullptr), hasValidScript(false) {
 }
 
 ScriptEngine::~ScriptEngine() {
@@ -37,54 +37,105 @@ bool ScriptEngine::Initialize() {
 }
 
 void ScriptEngine::Shutdown() {
+    ClearCachedFunctions();
     if (engine) {
         engine->ShutDownAndRelease();
         engine = nullptr;
     }
-    updateFunc = nullptr;
-    drawFunc = nullptr;
+    currentModule = nullptr;
+    hasValidScript = false;
 }
 
 bool ScriptEngine::CompileScript(const std::string& filename) {
     if (!engine) return false;
 
-    engine->GarbageCollect();
-    asIScriptModule* mod = engine->GetModule("main", asGM_ALWAYS_CREATE);
-
     std::string code = ReadFile(filename);
     if (code.empty()) {
         std::cerr << "Failed to read script file: " << filename << "\n";
         return false;
     }
 
-    int r = mod->AddScriptSection(filename.c_str(), code.c_str());
-    if (r < 0) return false;
+    // Try to compile in a temporary module first
+    asIScriptModule* tempMod = engine->GetModule("temp", asGM_ALWAYS_CREATE);
+    
+    int r = tempMod->AddScriptSection(filename.c_str(), code.c_str());
+    if (r < 0) {
+        std::cerr << "Failed to add script section for: " << filename << "\n";
+        engine->DiscardModule("temp");
+        return false;
+    }
 
-    r = mod->Build();
-    if (r < 0) return false;
+    r = tempMod->Build();
+    if (r < 0) {
+        std::cerr << "Failed to build script: " << filename << "\n";
+        engine->DiscardModule("temp");
+        return false;
+    }
 
-    // Cache Update(float dt) and Draw() functions if they exist
-    updateFunc = mod->GetFunctionByName("Update");
-    drawFunc = mod->GetFunctionByName("Draw");
+    // If we get here, compilation succeeded
+    // Now safely replace the main module
+    if (currentModule) {
+        engine->DiscardModule("main");
+    }
+    
+    // Create new main module with the working code
+    currentModule = engine->GetModule("main", asGM_ALWAYS_CREATE);
+    r = currentModule->AddScriptSection(filename.c_str(), code.c_str());
+    if (r >= 0) {
+        r = currentModule->Build();
+    }
+    
+    // Clean up temp module
+    engine->DiscardModule("temp");
+    
+    if (r < 0) {
+        // This shouldn't happen since we already tested compilation
+        std::cerr << "Unexpected error when creating main module\n";
+        ClearCachedFunctions();
+        return false;
+    }
+
+    // Cache new functions
+    updateFunc = currentModule->GetFunctionByName("Update");
+    drawFunc = currentModule->GetFunctionByName("Draw");
+    hasValidScript = true;
 
     std::cout << "Script compiled and cached: " << filename << "\n";
     return true;
 }
 
 void ScriptEngine::CallScriptFunction(asIScriptFunction* func, float dt) {
-    if (!func || !engine) return;
+    if (!func || !engine || !hasValidScript) return;
 
     asIScriptContext* ctx = engine->CreateContext();
-    ctx->Prepare(func);
+    if (!ctx) return;
+
+    int r = ctx->Prepare(func);
+    if (r < 0) {
+        ctx->Release();
+        return;
+    }
 
     if (func->GetParamCount() == 1) {
         ctx->SetArgFloat(0, dt);
     }
 
-    ctx->Execute();
+    r = ctx->Execute();
+    if (r != asEXECUTION_FINISHED) {
+        if (r == asEXECUTION_EXCEPTION) {
+            std::cerr << "Script exception: " << ctx->GetExceptionString() << "\n";
+        }
+    }
+
     ctx->Release();
 }
 
+void ScriptEngine::ClearCachedFunctions() {
+    updateFunc = nullptr;
+    drawFunc = nullptr;
+    hasValidScript = false;
+}
+
 void ScriptEngine::GarbageCollect() {
     if (engine) {
         engine->GarbageCollect();