message: Remove unwrap from `get_key_values_by_prefix`
diff: @@ -485,13 +485,14 @@ impl IndexApi<TezedgeContext> for TezedgeIndex {
  prefix: &ContextKey,
  ) -> Result<Option<Vec<(ContextKeyOwned, ContextValue)>>, ContextError> {
  let context_hash_arr: EntryHash = context_hash.as_ref().as_slice().try_into()?;
  - // TODO: this could be done without implementing the functiontionality in the tree,
  - // move that code to the index.
  - let context = self.checkout(context_hash)?.unwrap();
  - context
  + let context = self.checkout(context_hash)?;
  + match context {
  + None => Ok(None),
  + Some(context) => Ok(context
  .tree
  .get_key_values_by_prefix(&context_hash_arr, prefix)
  - .map_err(ContextError::from)
  + .map_err(ContextError::from)?),
  + }
  }
  fn get_context_tree_by_prefix(
  