fix: resolve IDB nil-on-channel and CLJS deref bugs

- idb/get-meta and idb/get-doc were calling (put! ch nil) when no
  result found, which is illegal in core.async. Now close the channel
  instead (reader gets nil from closed channel).
- todomvc.cljs used @(!todos) which calls the atom as a function.
  Fixed to @@!todos (deref atom → deref SyncedAtom).

src/pocketbook/idb.cljs

@@ -100,14 +100,15 @@
     (set! (.-onsuccess req)
       (fn [e]
         (let [result (.-result (.-target e))]
-          (put! ch (when result
-                     {:id      (.-id result)
-                      :value   (decode (.-value result))
-                      :version (.-version result)
-                      :updated (.-updated result)
-                      :deleted (.-deleted result)
-                      :synced  (.-synced result)}))
-          (async/close! ch))))
+          (if result
+            (do (put! ch {:id      (.-id result)
+                          :value   (decode (.-value result))
+                          :version (.-version result)
+                          :updated (.-updated result)
+                          :deleted (.-deleted result)
+                          :synced  (.-synced result)})
+                (async/close! ch))
+            (async/close! ch)))))
     (set! (.-onerror req)
       (fn [e] (js/console.error "IDB get error:" e) (async/close! ch)))
     ch))
@@ -196,8 +197,10 @@
     (set! (.-onsuccess req)
       (fn [e]
         (let [result (.-result (.-target e))]
-          (put! ch (when result (.-value result)))
-          (async/close! ch))))
+          (if result
+            (do (put! ch (.-value result))
+                (async/close! ch))
+            (async/close! ch)))))
     (set! (.-onerror req) (fn [_] (async/close! ch)))
     ch))
 

src/pocketbook/todomvc.cljs

@@ -20,7 +20,7 @@
 (defn- todos-list
   "Return todos as sorted vec of [id doc] pairs."
   []
-  (->> @(!todos)
+  (->> @@!todos
        (sort-by (fn [[_ doc]] (:created doc)))
        vec))