parser yang BUGFIX avoid accessing memory after input buffer
diff --git a/src/parser_yang.c b/src/parser_yang.c
index 58449ae..9fef72a 100644
--- a/src/parser_yang.c
+++ b/src/parser_yang.c
@@ -838,6 +838,8 @@
         /* fall through */
         default:
             MOVE_INPUT(ctx, 1);
+        /* fall through */
+        case '\0':
             LOGVAL_PARSER(ctx, LY_VCODE_INSTREXP, (int)(ctx->in->current - word_start), word_start,
                     "a keyword followed by a separator");
             return LY_EVALID;