Clear buffered input when a reader raise an error

so that subsequent read won't be confused.
#1078

ChangeLog

@@ -1,5 +1,8 @@
 2024-11-07  Shiro Kawai  <[email protected]>
 
+	* lib/gauche/interactive/editable-reader.scm (make-editable-reader):
+	  Clear buffered input when a reader raise an error, so that
+	  subsequent read won't be confused.
 	* src/gauche.h (SCM_CHAR_MAX): Change SCM_CHAR_MAX to 0x10ffff.
 	  We intentionally took wider range for the room of extension,
 	  but now that internal encoding is fixed to utf-8 and more

lib/gauche/interactive/editable-reader.scm

@@ -66,7 +66,12 @@
           [buffer (open-input-string "")])
       (define (read-1 reader)
         (rec (try)
-          (let1 x (reader buffer)
+          (let1 x (guard (e [(is-a? e <read-error>)
+                             ;; discard remaining input so that subsequent
+                             ;; read won't be confused
+                             (set! buffer (open-input-string ""))
+                             (raise e)])
+                    (reader buffer))
             (if (eof-object? x)
               (let1 input (read-line/edit ctx)
                 (if (eof-object? input)