Add a test to cover the newly discovered nil case

test/re-frame/interceptor_test.cljs

@@ -45,6 +45,20 @@
       (is (= (get-effect a :db)          ;; test after
              {:1 {:2 :4}})))))
 
+(deftest test-path-with-nil-db
+  (let [db  {:1 {:2 :target}}
+        p  (path [:1 :2])]    ;; a two level path
+
+    (let [b4 (-> (context [] [] db)
+                 ((:before p)))           ;; before
+          a (-> b4
+                (assoc-effect :db nil)   ;; <-- db becomes nil
+                ((:after p)))]           ;; after
+
+      (is (= (get-coeffect b4 :db))      ;; test before
+          :target)
+      (is (= (get-effect a :db)          ;; test after
+             {:1 {:2 nil}})))))
 
 (deftest test-db-handler-interceptor
   (let [event   [:a :b]