Fix bad whenComplete

Author: cosineblast

src/manifold/deferred.clj

@@ -1649,12 +1649,21 @@
 
     result))
 
-(defn- when-complete [this ^java.util.function.BiConsumer operator]
-  (assert-some operator)
-  (on-realized this
-               #(.accept operator % nil)
-               #(.accept operator nil %))
-  this)
+(defn- when-complete [d ^BiConsumer f]
+  (assert-some f)
+  (let [d' (deferred)]
+    (on-realized d
+                 (fn [val]
+                   (try (.accept f val nil)
+                        (success! d' val)
+                        (catch Throwable err
+                          (error! d' err))))
+                 (fn [err]
+                   (try (.accept f nil err)
+                        (error! d' err)
+                        (catch Throwable _
+                          (error! d' err)))))
+    d'))
 
 (def ^:private when-complete-async (async-for when-complete))
 

test/manifold/deferred_stage_test.clj

@@ -524,7 +524,25 @@
 
     (is (thrown? RuntimeException @d1))
     (is (thrown? RuntimeException @d2))
-    (is (= true @was-called))))
+    (is (= true @was-called)))
+
+  (let [d1 (d/success-deferred 1)
+        d2 (method
+            d1
+            (fn->BiConsumer (fn [_ _] (throw (RuntimeException.))))
+            executor)]
+
+    (is (thrown? RuntimeException @d2)))
+
+(let [error (RuntimeException. "d1 error")
+      d1 (d/error-deferred error)
+        d2 (method
+            d1
+            (fn->BiConsumer (fn [_ _]
+                              (throw (RuntimeException. "d2 error"))))
+            executor)]
+
+    (is (thrown-with-msg? RuntimeException #"d1 error" @d2))))
 
 (deftest test-when-complete