[niepce] npc-fwk: fix a clippy warning

[Hubert Figuière <hub src gnome org>]

commit 648f762a401dd9a5774b07b2d072736655e7651a
Author: Hubert Figuière <hub figuiere net>
Date:   Mon May 23 22:14:26 2022 -0400

    npc-fwk: fix a clippy warning

 crates/npc-fwk/src/toolkit.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/crates/npc-fwk/src/toolkit.rs b/crates/npc-fwk/src/toolkit.rs
index c9538e3..ba377d4 100644
--- a/crates/npc-fwk/src/toolkit.rs
+++ b/crates/npc-fwk/src/toolkit.rs
@@ -32,7 +32,7 @@ pub struct PortableChannel<T>(pub Sender<T>);
 pub fn thread_context() -> glib::MainContext {
     glib::MainContext::thread_default().unwrap_or_else(|| {
         let ctx = glib::MainContext::new();
-        ctx.with_thread_default(|| true);
+        on_err_out!(ctx.with_thread_default(|| true));
         ctx
     })
 }