thaw API should throw on first non-legacy error

README.md

@@ -2,7 +2,7 @@ Current [semantic](http://semver.org/) version:
 
 ```clojure
 [com.taoensso/nippy "1.2.1"]        ; Stable
-[com.taoensso/nippy "2.0.0-alpha9"] ; Development (notes below)
+[com.taoensso/nippy "2.0.0-alpha10"] ; Development (notes below)
 ```
 
 v2 adds pluggable compression, crypto support (also pluggable), an improved API (including much better error messages), easier integration into other tools/libraries, and hugely improved performance. It **is backwards compatible**, but please note that the old `freeze-to-bytes`/`thaw-from-bytes` API has been **deprecated** in favor of `freeze`/`thaw`. **PLEASE REPORT ANY PROBLEMS!**

project.clj

@@ -1,4 +1,4 @@
-(defproject com.taoensso/nippy "2.0.0-alpha9"
+(defproject com.taoensso/nippy "2.0.0-alpha10"
   :description "Clojure serialization library"
   :url "https://github.com/ptaoussanis/nippy"
   :license {:name "Eclipse Public License"

src/clj/taoensso/nippy.clj

@@ -296,7 +296,7 @@
     (if-let [[data-ba {:keys [unrecognized-header? compressed? encrypted?]
                        :as   head-meta}] (try-parse-header ba)]
 
-      (cond ; Header appears okay
+      (cond ; Header _appears_ okay
        (and (not legacy-opts) unrecognized-header?) ; Conservative
        (ex "Unrecognized header. Data frozen with newer Nippy version?")
        (and compressed? (not compressor))
@@ -305,10 +305,15 @@
        (if (::tools-thaw? opts) ::need-password
            (ex "Encrypted data. Try again with password."))
        :else (try (try-thaw-data data-ba head-meta)
-                  (catch Exception _ (try-thaw-data ba nil))))
+                  (catch Exception e
+                    (if legacy-opts
+                      (try-thaw-data ba nil)
+                      (throw e)))))
 
       ;; Header definitely not okay
-      (try-thaw-data ba nil))))
+      (if legacy-opts
+        (try-thaw-data ba nil)
+        (ex "Unfrozen or corrupt data?")))))
 
 (comment (thaw (freeze "hello"))
          (thaw (freeze "hello" {:compressor nil}))