Fix SAFE-SIMPLE-READ-FROM-StrING

READER-ERROR doesn't take usual SIMPLE-ERROR args. (it does in Allegro though)

* safe-simple-read.lisp (snooze-reader-error): New error
condition.
(read-string, parse-symbol)
(safe-simple-read-from-string): Use it.

safe-simple-read.lisp

 (in-package #:snooze-safe-simple-read)
 
+(define-condition snooze-reader-error (simple-error reader-error) ())
+
 (defun parse-integer-then-float (string)
   (let (retval nread)
     (multiple-value-setq (retval nread)
@@ -15,7 +17,7 @@
 
 (defun read-string (stream &optional (terminator #\") )
   (unless (eq (read-char stream) terminator)
-    (error 'reader-error
+    (error 'snooze-reader-error
            :format-control "~a cannot read string that doesn't start with ~a"
            :format-arguments (list 'parse-string terminator)))
   (let ((nread 1))
@@ -32,7 +34,7 @@
                (t
                 (write-char c)))))
        (end-of-file (e)
-         (error 'reader-error
+         (error 'snooze-reader-error
                 :format-control "~a sees premature end reading string inside string (~a)"
                 :format-arguments (list 'parse-string e))))
      nread)))
@@ -76,27 +78,29 @@
                                count 1
                                finally (unread-char c stream))
                        (end-of-file (e)
-                         (error 'reader-error
+                         (error 'snooze-reader-error
                                 :format-control "~a sees a colon ending reading symbol from string ~a (~a)"
                                 :format-arguments (list 'parse-symbol string e)))))
                (cond ((= ncolons 0)
-                      (error 'reader-error
+                      (error 'snooze-reader-error
                              :format-control "~a expecting colons reading symbol from string ~a"
                              :format-arguments (list 'parse-symbol string)))
                      ((> ncolons 2)
-                      (error 'reader-error
+                      (error 'snooze-reader-error
                              :format-control "~a sees too many colons reading symbol from string ~a"
                              :format-arguments (list 'parse-symbol string))))
-               (setq package (or (find-package name)
-                                 (error 'reader-error
-                                        :format-control "~a sees does not recognize package ~a"
+               (setq package (or (and (zerop (length name))
+                                      #.(find-package :keyword))
+                                 (find-package name)
+                                 (error 'snooze-reader-error
+                                        :format-control "~a does not recognize package ~a"
                                         :format-arguments (list 'parse-symbol name))))
                (multiple-value-bind (name more-nread)
                    (read-name stream)
                  (setq symbol-name name
                        nread (+ ncolons nread more-nread))
                  (when (/= nread (length string))
-                   (error 'reader-error
+                   (error 'snooze-reader-error
                           :format-control "~a sees garbage reading symbol from string ~a"
                           :format-arguments (list 'parse-symbol string)))))
               (t
@@ -106,7 +110,7 @@
       (when (and (eq status :internal)
                  ncolons
                  (/= ncolons 2))
-        (error 'reader-error
+        (error 'snooze-reader-error
                :format-control "~a sees a symbol ~a not external in the ~a package"
                :format-arguments (list 'parse-symbol symbol-name package)))
       (values symbol status symbol-name package))))
@@ -132,7 +136,7 @@ is never interned anywhere"
            (multiple-value-bind (obj nread)
                (read-string stream #\")
              (unless (= nread (length string))
-               (error 'reader-error
+               (error 'snooze-reader-error
                       :format-control "~a sees junk reading string inside string ~s"
                       :format-arguments (list 'safe-read-simple-token-from-string string)))
              (values obj nread))))
@@ -149,7 +153,7 @@ is never interned anywhere"
                         (if make-symbol-p
                             (values (make-symbol symbol-name)
                                     (length string))
-                            (error 'reader-error
+                            (error 'snooze-reader-error
                                    :format-control "~a refusing to intern a new symbol ~s in ~a"
                                    :format-arguments `(safe-simple-read-from-string
                                                        ,string