fix subselect changing first matched element to nil when transformed to empty sequence

CHANGES.md

@@ -4,6 +4,7 @@
 * Add `vterminal` that takes in collected vals as vector in first argument rather than spliced into argument list.
 * Add `compact` navigator. After each step of navigation of its subpath, `compact` removes the collection if it's empty.
 * Change `terminal` to be a no-op on select codepath
+* Bug fix: `subselect`/`filterer` removes first matched element instead of setting to nil when transformed to empty sequence
 
 ## 1.0.5
 

src/clj/com/rpl/specter.cljc

@@ -895,7 +895,7 @@
             values-to-insert (i/mutable-cell transformed)]
         (compiled-transform late
                             (fn [_] (let [vs (i/get-cell values-to-insert)]
-                                      (if vs
+                                      (if (seq vs)
                                         (do (i/update-cell! values-to-insert next)
                                             (first vs))
                                         NONE

test/com/rpl/specter/core_test.cljc

@@ -1535,6 +1535,8 @@
 
 (deftest filterer-remove-test
   (is (= [1 :a 3 5] (setval (s/filterer even?) [:a] [1 2 3 4 5])))
+  (is (= [1 3 5] (setval (s/filterer even?) [] [1 2 3 4 5])))
+  (is (= [1 3 5] (setval (s/filterer even?) nil [1 2 3 4 5])))
   )
 
 (deftest helper-preds-test