This error occurs when the index being accessed is out of range for the tuple. In this case, it seems that the error is occurring in the line:
```
attn1_out = LayerNormalization()(attn1_out + gru1out)
```
It's possible that `attn1_out` and `gru1out` have different shapes or dimensions, causing an indexing error when trying to add them together.
To fix this error, you can try printing the shapes of `attn1_out` and `gru1out` before the line above to see if they match. If they don't match, you may need to reshape or transpose one of the tensors to match the other.