Error searching for ingredients

Searching for certain phrases or ingredients (that is used in at least one recipe), such as `cook search tuna`, returns:

`Error: Failed to read '/data/recipes'`

`Caused by:`
` stream did not contain valid UTF-8`

The path to the recipes directory is correct and other searches work. Running `cook doctor` in the same directory identifies tuna as an ingredient that is used in a recipe but not in `aisle.conf`.

A search for an ingredient that is not used in at least one recipe returns nothing.

cookcli 0.35.0

Reproduce the failure with `cook search tuna` in the reported recipe directory, then compare it with a search for an unused ingredient and the output of `cook doctor`. Trace the ingredient-search path and its recipe-directory reading until the invalid UTF-8 error is explained. Done means valid ingredient searches no longer fail and the behavior is covered by a regression test.

Written by the indexing model from the issue text.