Force is_decoder=True to fix generate ValueError

defake/blipmodels/blip.py

@@ -123,9 +123,10 @@ class BLIP_Decoder(nn.Module):
         med_config = BertConfig.from_json_file(med_config)
         med_config.encoder_width = vision_width
         
+        med_config.is_decoder = True
+        med_config.add_cross_attention = True
+        
         self.text_decoder = BertLMHeadModel(config=med_config)    
-        self.text_decoder.config.is_decoder = True
-        self.text_decoder.config.add_cross_attention = True
         
         self.prompt = prompt
         self.prompt_length = len(self.tokenizer(self.prompt).input_ids)-1