Add rudimentary error management to loader callbacks.

src/loaders/blend.nim

@@ -101,9 +101,9 @@ method openAssetFile*(self: BlendLoader, path: string) =
     # self.on_destroy = OnDestroy(destructor: proc() = self.close())
     self.blend_file_path = path
 
-proc loadAsync(self: BlendLoader, callback: proc()) =
+proc loadAsync(self: BlendLoader, callback: proc(err: string)) =
     if self.blend_file != nil:
-        callback()
+        callback("")
     else:
         self.close()
         self.resource = loadUri(self.blend_file_path,
@@ -111,9 +111,7 @@ proc loadAsync(self: BlendLoader, callback: proc()) =
                 self.resource = nil
                 if ok:
                     self.blend_file = openBlendFile(self.blend_file_path, data.data, data.byte_len)
-                    callback()
-                else:
-                    raise IOError.newException err
+                callback(err)
         )
 
 type BlenderObTypes = enum
@@ -573,9 +571,12 @@ proc get_active_scene_name(self: BlendLoader): string =
         if scene.valid:
             return scene.id.name.str[2 .. ^1]
 
-method loadScene*(self: BlendLoader, name: string="", scene: Scene=nil, callback: proc(scene: Scene)) =
+method loadScene*(self: BlendLoader, name: string="", scene: Scene=nil, callback: proc(err: string, scene: Scene)) =
     assert self.blend_file_path != "", "Blend file is not loaded"
-    self.loadAsync proc() =
+    self.loadAsync proc(err: string) =
+        if err != "":
+            callback(err, nil)
+            return
         assert self.blend_file != nil, "Error loading blend file " & self.blend_file_path
         var name = name
         if name == "":
@@ -588,8 +589,19 @@ method loadScene*(self: BlendLoader, name: string="", scene: Scene=nil, callback
                 let was_first_scene = self.engine.scenes.len == 0
                 if scene == nil:
                     scene = self.engine.new_scene(name=name)
-                self.loadSceneImpl(node, scene)
-                callback(scene)
+                try:
+                    self.loadSceneImpl(node, scene)
+                except Exception as e:
+                    for line in e.getStackTrace.split '\n':
+                        echo line
+                    echo getCurrentExceptionMsg()
+                    scene.destroy()
+                    callback(getCurrentExceptionMsg(), nil)
+                    return
+                callback("", scene)
+                if scene.name notin self.engine.new_scenes:
+                    # it was deleted
+                    return
                 # TODO: when loading is async, move this stuff after loading has
                 # finished
                 if was_first_scene and not scene.enabled:

src/loaders/loader_base.nim

@@ -39,7 +39,7 @@ when defined(nimdoc):
 method openAssetFile*(self: Loader, path: string) {.base.} =
     discard
 method loadScene*(self: Loader, name: string="", scene: Scene=nil, 
-    callback: proc(scene: Scene)) {.base.} =
+    callback: proc(err: string, scene: Scene)) {.base.} =
     discard
 method loadImageImpl*(self: Loader) {.base.} =
     discard

src/myou_engine.nim

@@ -201,7 +201,7 @@ proc run*(self: MyouEngine) =
     when not defined(nimdoc):
         start_platform_main_loop(self, myou_main_loop)
 
-proc loadScene*(self: MyouEngine, uri: string, callback: proc(scene: Scene), name = "", ext = "") =
+proc loadScene*(self: MyouEngine, uri: string, callback: proc(err: string, scene: Scene), name = "", ext = "") =
     let ext = if ext == "":
         uri.rsplit('.', 1)[1]
     else: