[FlaxGenerate] Fix bug in decoder_start_token_id (#17035)

src/transformers/generation_flax_utils.py

@@ -264,7 +264,7 @@ class FlaxGenerationMixin:
         pad_token_id = pad_token_id if pad_token_id is not None else self.config.pad_token_id
         eos_token_id = eos_token_id if eos_token_id is not None else self.config.eos_token_id
         decoder_start_token_id = (
-            decoder_start_token_id if decoder_start_token_id else self.config.decoder_start_token_id
+            decoder_start_token_id if decoder_start_token_id is not None else self.config.decoder_start_token_id
         )
         prng_key = prng_key if prng_key is not None else jax.random.PRNGKey(0)