How to write a simple error interceptor?

Question

Here's my first attempt of a catcher interceptor on Pedestal:

(definterceptorfn catcher []
   (interceptor
   :error (fn [context error]
           {:status 500 
            :body (->> error .toString (hash-map :error) json/write-str)
            :headers {"Content-type" "application/json"}})))

As I could test, by adding (/ 1 0) to my code, the function does get called, but the client gets an empty response with status 200, instead of the response in the map. I wonder why it is so.

There is nothing fancy in my routes variable:

(defroutes routes
  [[["/api"
     ^:interceptors [(body-params/body-params) (catcher) bootstrap/html-body]
     ...

Answer 1

As Tim Ewald explained, I was returning a response map when a context was needed.

Fixed with

(definterceptorfn catcher []
   (interceptor
   :error (fn [context error]
           (assoc context :response
            {:status 500 
             :body (->> error .toString (hash-map :error) json/write-str)
             :headers {"Content-type" "application/json"}}))))