Fix #1041: Improve error message when regex literal in EDN config (#1230)

* Improve error message when regex literal in EDN config (#1041)

Regex literal syntax (example: #"^foo") is not allowed in EDN. With the
ability to write tasks in the config file, users may mistakenly try to
include regex literals. This patch improves the error message by
informing the user that literal regex syntax is not allowed and
recommends using re-pattern instead.

* Update changelog

* Fixup main.clj

* Fixup changelog

CHANGELOG.md

@@ -5,6 +5,10 @@ For a list of breaking changes, check [here](#breaking-changes).
 A preview of the next release can be installed from
 [babashka-dev-builds](https://github.com/babashka/babashka-dev-builds).
 
+## 0.8.1 (TBD)
+
+- [#1041](https://github.com/babashka/babashka/issues/1041): Improve error message when regex literal in EDN config
+
 ## 0.8.0 (2022-04-04)
 
 ### New

src/babashka/main.clj

@@ -964,6 +964,13 @@ Use bb run --help to show this help output.
                  (and (= minor-current minor-min)
                       (>= patch-current patch-min)))))))
 
+(defn load-edn [string]
+  (try (edn/read-string string)
+    (catch java.lang.RuntimeException e
+      (if (re-find #"No dispatch macro for: \"" (.getMessage e))
+        (throw (ex-info "Invalid regex literal found in EDN config, use re-pattern instead" {}))
+        (throw e)))))
+
 (defn main [& args]
   (let [[args global-opts] (parse-global-opts args)
         {:keys [:jar] :as file-opt} (when (some-> args first io/file .isFile)
@@ -977,7 +984,7 @@ Use bb run --help to show this help output.
         bb-edn (when bb-edn-file
                  (System/setProperty "babashka.config" bb-edn-file)
                  (let [raw-string (slurp bb-edn-file)
-                       edn (edn/read-string raw-string)
+                       edn (load-edn raw-string)
                        edn (assoc edn
                                   :raw raw-string
                                   :file bb-edn-file)

test/babashka/bb_edn_test.clj

@@ -200,6 +200,12 @@
       (is (thrown-with-msg?
            Exception #"Cyclic task: b"
            (bb "run" "b")))))
+  (testing "friendly regex literal error handling"
+    (test-utils/with-config
+     "{:tasks {something (clojure.string/split \"1-2\" #\"-\")}}"
+     (is (thrown-with-msg?
+          Exception #"Invalid regex literal"
+          (bb "run" "something")))))
   (testing "doc"
     (test-utils/with-config '{:tasks {b {:doc "Beautiful docstring"}}}
       (let [s (test-utils/bb nil "doc" "b")]