Hi, your script is calling the CDS daily application, which does not support accumulated fields (such as precipitation) from ERA5-land hourly data. This is because for ERA5-Land hourly data, the accumulated values are stored as the total since 0000 on a given day.
This means that the daily total for a given day is simply the data from the 0000 timestep of the following day (e.g. 0000 on 2nd January2024 contains the total precipitation for 1st January 2024). So for this dataset, you do not need to calculate the daily sum, as it already exists.
See the ERA5-Land documentation for details.
hope that helps
Kevin