fix(texture): guard render-thread teardown against engine shutdown

The render-thread teardown task posted by UnregisterTexture() captured a
raw engine pointer and only checked that the engine existed at post time.
If the engine shuts down before the task runs (PostRenderThreadTask then
runs it inline), calling gl_renderer->OnMakeCurrent() and
engine->UnregisterExternalTexture() touches an already-destroyed GL context
and a null engine handle.

Guard both calls with engine->IsRunning() inside the task; tex.reset() and
the completion callback still run unconditionally so the texture is released
and callers (e.g. webview_flutter_lwe) always get their 'safe to free'
signal.

Also reflow the FlutterDesktopTextureRegistrarUnregisterExternalTexture call
to satisfy clang-format.

Author: seungsoo47

flutter/shell/platform/tizen/flutter_tizen.cc

@@ -330,8 +330,8 @@ void FlutterDesktopTextureRegistrarUnregisterExternalTexture(
     int64_t texture_id,
     void (*callback)(void* user_data),
     void* user_data) {
-  TextureRegistrarFromHandle(texture_registrar)->UnregisterTexture(
-      texture_id, callback, user_data);
+  TextureRegistrarFromHandle(texture_registrar)
+      ->UnregisterTexture(texture_id, callback, user_data);
 }
 
 bool FlutterDesktopTextureRegistrarMarkExternalTextureFrameAvailable(

flutter/shell/platform/tizen/flutter_tizen_texture_registrar.cc

@@ -110,11 +110,20 @@ bool FlutterTizenTextureRegistrar::UnregisterTexture(int64_t texture_id,
         // glDeleteTextures in the texture's destructor targets the correct
         // context (the engine does not guarantee a current context when
         // running posted tasks).
-        if (gl_renderer) {
+        //
+        // The engine may have shut down between PostRenderThreadTask() being
+        // called and this task running, in which case the GL context is
+        // already gone and the engine handle is null; skip the GL/engine
+        // calls in that case but still release the texture and fire the
+        // completion callback.
+        const bool is_running = engine->IsRunning();
+        if (is_running && gl_renderer) {
           gl_renderer->OnMakeCurrent();
         }
         tex.reset();
-        engine->UnregisterExternalTexture(texture_id);
+        if (is_running) {
+          engine->UnregisterExternalTexture(texture_id);
+        }
         if (callback) {
           callback(user_data);
         }