🐛 Fix index-of-pred early termination on nil elements

The index-of-pred function used (nil? c) to detect end-of-collection,
which caused premature termination when the collection contained nil
values. Rewrite using (seq coll) / (next s) pattern to correctly
distinguish between nil elements and end-of-sequence.

common/src/app/common/data.cljc

@@ -291,15 +291,12 @@
 
 (defn index-of-pred
   [coll pred]
-  (loop [c    (first coll)
+  (loop [s     (seq coll)
-         coll (rest coll)
          index 0]
-    (if (nil? c)
+    (when s
-      nil
+      (if (pred (first s))
-      (if (pred c)
         index
-        (recur (first coll)
+        (recur (next s)
-               (rest coll)
                (inc index))))))
 
 (defn index-of

common/test/common_tests/data_test.cljc

@@ -372,12 +372,19 @@
   (t/is (= 0 (d/index-of-pred [1 2 3] odd?)))
   (t/is (= 1 (d/index-of-pred [2 3 4] odd?)))
   (t/is (nil? (d/index-of-pred [2 4 6] odd?)))
-  (t/is (nil? (d/index-of-pred [] odd?))))
+  (t/is (nil? (d/index-of-pred [] odd?)))
+  ;; works correctly when collection contains nil elements
+  (t/is (= 2 (d/index-of-pred [nil nil 3] some?)))
+  (t/is (= 0 (d/index-of-pred [nil 1 2] nil?)))
+  ;; works correctly when collection contains false elements
+  (t/is (= 1 (d/index-of-pred [false true false] true?))))
 
 (t/deftest index-of-test
   (t/is (= 0 (d/index-of [:a :b :c] :a)))
   (t/is (= 2 (d/index-of [:a :b :c] :c)))
-  (t/is (nil? (d/index-of [:a :b :c] :z))))
+  (t/is (nil? (d/index-of [:a :b :c] :z)))
+  ;; works when searching for nil in a collection
+  (t/is (= 1 (d/index-of [:a nil :c] nil))))
 
 (t/deftest replace-by-id-test
   (let [items [{:id 1 :v "a"} {:id 2 :v "b"} {:id 3 :v "c"}]