From bbd4ee54ca72dc2ddc846fc48c3faba099d6cc18 Mon Sep 17 00:00:00 2001
From: kingbri <bdashore3@proton.me>
Date: Tue, 2 Jan 2024 01:38:03 -0500
Subject: [PATCH] Model: Add fallback if negative prompt is empty

Fallback to the BOS token since an empty string won't do anything.
Ideally, an empty negative prompt should not be used, but it's not
the end of the world.

Signed-off-by: kingbri <bdashore3@proton.me>
---
 model.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/model.py b/model.py
index d61512fc..cef53c34 100644
--- a/model.py
+++ b/model.py
@@ -585,7 +585,11 @@ def generate_gen(self, prompt: str, **kwargs):
         if cfg_scale not in [None, 1.0]:
             if self.use_cfg:
                 gen_settings.cfg_scale = cfg_scale
-                negative_prompt = kwargs.get("negative_prompt")
+
+                # If the negative prompt is empty, use the BOS token
+                negative_prompt = unwrap(
+                    kwargs.get("negative_prompt"), self.tokenizer.bos_token
+                )
             else:
                 logger.warn(
                     "CFG is currently disabled. "