Handle syntax-set loading errors

src/assets.rs

@@ -43,7 +43,7 @@ impl HighlightingAssets {
                 syntax_dir.to_string_lossy()
             ).into());
         }
-        let _ = syntax_set.load_syntaxes(syntax_dir, true);
+        syntax_set.load_syntaxes(syntax_dir, true)?;
         syntax_set.load_plain_text_syntax();
 
         Ok(HighlightingAssets {

src/main.rs

@@ -40,6 +40,7 @@ mod errors {
         foreign_links {
             Clap(::clap::Error);
             Io(::std::io::Error);
+            SyntectError(::syntect::LoadingError);
         }
     }