error report is propagated through pic->err

include/picrin.h

@@ -110,7 +110,7 @@ typedef struct {
   struct pic_lib *lib;
 
   jmp_buf *jmp;
-  const char *errmsg;
+  struct pic_error *err;
 
   struct pic_heap *heap;
   struct pic_object *arena[PIC_ARENA_SIZE];
@@ -210,6 +210,8 @@ NORETURN void pic_error(pic_state *, const char *);
 NORETURN void pic_errorf(pic_state *, const char *, size_t, ...);
 void pic_warn(pic_state *, const char *);
 
+const char *pic_errmsg(pic_state *);
+
 void pic_debug(pic_state *, pic_value);
 void pic_fdebug(pic_state *, pic_value, XFILE *);
 

include/picrin/error.h

@@ -14,9 +14,10 @@ struct pic_error {
   enum pic_error_kind {
     PIC_ERROR_OTHER,
     PIC_ERROR_FILE,
-    PIC_ERROR_READ
+    PIC_ERROR_READ,
+    PIC_ERROR_RAISED
   } type;
-  char *msg;
+  struct pic_string *msg;
   pic_value irrs;
 };