CLJS-2002: Don't throw when no *print-fn* is set

Author: mfikes

src/main/cljs/cljs/core.cljs

@@ -65,17 +65,13 @@
   ^{:doc "Each runtime environment provides a different way to print output.
   Whatever function *print-fn* is bound to will be passed any
   Strings which should be printed." :dynamic true}
-  *print-fn*
-  (fn [_]
-    (throw (js/Error. "No *print-fn* fn set for evaluation environment"))))
+  *print-fn* nil)
 
 (defonce
   ^{:doc "Each runtime environment provides a different way to print error output.
   Whatever function *print-err-fn* is bound to will be passed any
   Strings which should be printed." :dynamic true}
-  *print-err-fn*
-  (fn [_]
-    (throw (js/Error. "No *print-err-fn* fn set for evaluation environment"))))
+  *print-err-fn* nil)
 
 (defn set-print-fn!
   "Set *print-fn* to f."
@@ -9584,6 +9580,8 @@ reduces them without incurring seq initialization"
     (-write writer s)))
 
 (defn string-print [x]
+  (when (nil? *print-fn*)
+    (throw (js/Error. "No *print-fn* fn set for evaluation environment")))
   (*print-fn* x)
   nil)
 

src/main/cljs/cljs/pprint.cljs

@@ -806,7 +806,7 @@ The following keyword arguments can be passed with values:
             (binding [*out* base-writer]
               (pr object)))
           (if (true? optval)
-            (*print-fn* (str sb)))
+            (string-print (str sb)))
           (if (nil? optval)
             (str sb)))))))
 
@@ -815,7 +815,7 @@ The following keyword arguments can be passed with values:
    (let [sb (StringBuffer.)]
      (binding [*out* (StringBufferWriter. sb)]
        (pprint object *out*)
-       (*print-fn* (str sb)))))
+       (string-print (str sb)))))
   ([object writer]
    (with-pretty-writer writer
                        (binding [*print-pretty* true]
@@ -2736,7 +2736,7 @@ column number or pretty printing"
              (-flush wrapped-stream))))
        (cond
          (not stream) (str sb)
-         (true? stream) (*print-fn* (str sb))
+         (true? stream) (string-print (str sb))
          :else nil))))
   ([format args]
    (map-passing-context