On macOS, remove spurious error logging when handling Fn

Fixes rust-windowing#3246.

CHANGELOG.md

@@ -11,6 +11,8 @@ Unreleased` header.
 
 # Unreleased
 
+- On macOS, remove spurious error logging when handling `Fn`.
+
 # 0.29.4
 
 - Fix crash when running iOS app on macOS.

src/platform_impl/macos/event.rs

@@ -88,7 +88,9 @@ pub fn get_modifierless_char(scancode: u16) -> Key {
         return Key::Unidentified(NativeKey::MacOS(scancode));
     }
     if result_len == 0 {
-        log::error!("`UCKeyTranslate` was succesful but gave a string of 0 length.");
+        // This is fine - not all keys have text representation.
+        // For instance, users that have mapped the `Fn` key to toggle
+        // keyboard layouts will hit this code path.
         return Key::Unidentified(NativeKey::MacOS(scancode));
     }
     let chars = String::from_utf16_lossy(&string[0..result_len as usize]);