fix(runtime): fail closed on hemx request errors

Preserve pending recovery while making failed HTTP responses non-applicable as effects. The runtime now restores aria-busy with pending state and emits inspectable hemx:error details with HTTP status for failed requests.

req: runtime/005

req: convention/007

hemx-js/runtime/hemx.js

@@ -11,6 +11,7 @@
   const everyTimers = new WeakMap();
   const pendingClassStates = new WeakMap();
   const indicatorStates = new WeakMap();
+  const busyStates = new WeakMap();
   const disabledStates = new WeakMap();
   const sseSources = new WeakMap();
   const atomStores = new WeakMap();
@@ -75,6 +76,7 @@
   function showPending(el, on) {
     const klass = el.getAttribute("data-hemx-pending-class");
     if (klass) togglePendingClass(el, klass, on);
+    toggleBusy(el, on);
     const root = rootOf(el) || document;
     forEachElement(root, (i) => { if (i.hasAttribute("data-hemx-indicator")) toggleIndicator(i, on); });
     if (el.hasAttribute("data-hemx-disable-while-pending")) {
@@ -85,6 +87,23 @@
     }
   }
 
+  function toggleBusy(el, on) {
+    const state = busyStates.get(el);
+    if (on) {
+      if (state) state.count += 1;
+      else busyStates.set(el, { count: 1, value: el.getAttribute("aria-busy") });
+      el.setAttribute("aria-busy", "true");
+      return;
+    }
+    if (!state) return;
+    state.count -= 1;
+    if (state.count <= 0) {
+      if (state.value === null) el.removeAttribute("aria-busy");
+      else el.setAttribute("aria-busy", state.value);
+      busyStates.delete(el);
+    }
+  }
+
   function togglePendingClass(el, klass, on) {
     const state = pendingClassStates.get(el);
     if (on) {
@@ -169,6 +188,12 @@
     return url.href;
   }
 
+  function httpError(response) {
+    const error = new Error(`HTTP ${response.status}`);
+    error.status = response.status;
+    return error;
+  }
+
   async function send(el, eventName, source = el) {
     if (el.getAttribute("data-hemx-confirm") && !confirm(el.getAttribute("data-hemx-confirm"))) return;
     const { form, data, multipart } = formDataFor(el, eventName, source);
@@ -209,9 +234,10 @@
         signal: abort.signal,
       });
       if (pending.get(target)?.abort !== abort && policy === "latest") return;
+      if (!response.ok) throw httpError(response);
       await applyResponse(response, rootOf(target));
     } catch (error) {
-      if (error.name !== "AbortError") emit(rootOf(target), "hemx:error", String(error));
+      if (error.name !== "AbortError") emit(rootOf(target), "hemx:error", { message: String(error), status: error.status || null });
     } finally {
       if (pending.get(target)?.abort === abort) {
         pending.delete(target);