Page type-check: strict's flags that cost nothing, and catch variables as unknown (#235)

why(e) gives a caught error's message; each catch read e.message as any.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/util.ts

@@ -3,6 +3,8 @@
 // smoke test, not the type checker, is what makes sure a selector exists.
 const $ = (s: string, r: ParentNode = document): any => r.querySelector(s);
 const $$ = (s: string, r: ParentNode = document): any[] => [...r.querySelectorAll(s)];
+/// What went wrong, from whatever a catch caught: the page throws Errors, but a catch cannot know.
+const why = (e: unknown): string => e instanceof Error ? e.message : String(e);
 const esc = s => (s??'').replace(/[&<>"']/g,c=>({'&':'&amp;','<':'&lt;','>':'&gt;','"':'&quot;',"'":'&#39;'}[c]));
 // Icons: Font Awesome Free 7.3.1 by @fontawesome - https://fontawesome.com
 // License - https://fontawesome.com/license/free (Icons: CC BY 4.0). Embedded as SVG, only the
@@ -151,7 +153,7 @@ async function share(title: string, url: string, btn?){
   if(navigator.share){
     // Cancelling the sheet rejects too, and is not a failure worth a word.
     try{ await navigator.share({title, url}); }
-    catch(e){ if(e.name!=='AbortError') toast(e.message,true); }
+    catch(e){ if((e as Error)?.name!=='AbortError') toast(why(e),true); }
     return;
   }
   await copyText(url,btn);