HS: collectionExpressions +4 (then on click, undefined where, component template)

- parser: nil return in parse-cmd for feature keywords (on/init/def/behavior/live)
  so "then on click" correctly hands off to outer coll-feats loop
- compiler: cek-try wrap for undefined variable refs in coll-where compilation
  so "doesNotExist where it > 1" returns nil instead of throwing
- integration: hs-activate! detects script[type=text/hyperscript-template] and
  applies handler to DOM instances via hs-query-all(component attr) not to script el

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/hyperscript/compiler.sx

@@ -1107,13 +1107,21 @@
                     (hs-to-sx (nth ast 1))
                     (nth ast 2)))
                 ((= head (quote coll-where))
-                  (list
-                    (quote filter)
+                  (let
+                    ((raw-coll (hs-to-sx (nth ast 1))))
                     (list
-                      (quote fn)
-                      (list (quote it))
-                      (hs-to-sx (nth ast 2)))
-                    (hs-to-sx (nth ast 1))))
+                      (quote filter)
+                      (list
+                        (quote fn)
+                        (list (quote it))
+                        (hs-to-sx (nth ast 2)))
+                      (if
+                        (symbol? raw-coll)
+                        (list
+                          (quote cek-try)
+                          (list (quote fn) (list) raw-coll)
+                          (list (quote fn) (list (quote _e)) nil))
+                        raw-coll))))
                 ((= head (quote coll-sorted))
                   (list
                     (quote hs-sorted-by)