real fix for string_slice

interpreter/prim.c

@@ -234,17 +234,21 @@ void __string_slice(int dst_idx)
     Thunk* idx2 = arg(1);
         
     char* chars;
+    int full_length;
     
     if(str->desc == (Desc*) __STRING_PTR__)
     {
         chars = str->_string_ptr->chars;
+        full_length = str->_string_ptr->length;
     }
     else
     {
         chars = str->_array._chars;
+        full_length = str->_array.length;
     }
 
-    int length = idx2->_int - idx1->_int;
+    int length = idx2->_int - idx1->_int + 1;
+    if(idx1->_int  + length > full_length) length = full_length - idx1->_int;
     
     target = string_create(target, length);
     memcpy(target->_array._chars, chars + idx1->_int, length);