Making deletions will alter the collection.json file, hence the search function unusable because we access the collection using list indices.

here some example:
```python
from ragatouille import RAGPretrainedModel
from ragatouille.utils import get_wikipedia_page
import os
model = RAGPretrainedModel.from_pretrained("colbert-ir/colbertv2.0")
document_ids = ["miyazaki", "ghibli"]
my_documents = [get_wikipedia_page("Hayao_Miyazaki"), get_wikipedia_page("Studio_Ghibli")]
document_metadatas = [
{"entity": "person", "source": "wikipedia"},
{"entity": "organisation", "source": "wikipedia"},
]
index_path = model.index(
index_name="my_index_with_ids_and_metadata",
collection=my_documents, #type: ignore
document_ids=document_ids,
document_metadatas=document_metadatas,
)

res = model.search("hallo")
print(f"DEBUGPRINT[1]: test_add_delete.py:19: res={res}")
model.delete_from_index("miyazaki")
model.search("hallo")
```
last n lines output:
```bash
[Jun 11, 13:18:00] #> Persisted updated IVF to .ragatouille/colbert/indexes/my_index_with_ids_and_metadata/ivf.pid.pt
Successfully deleted documents with these IDs: miyazaki
DEBUGPRINT[1]: colbert.py:394: results=[([56, 58, 26, 89, 25, 65, 37, 67, 66, 57], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [7.035354137420654, 6.577218055725098, 6.416233062744141, 6.170261859893799, 6.167287349700928, 5.608134746551514, 5.600253105163574, 5.547395706176758, 5.471892356872559, 5.340466022491455])]
Traceback (most recent call last):
File "/home/carlesoctav/.pyenv/versions/3.10.14/lib/python3.10/runpy.py", line 196, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/home/carlesoctav/.pyenv/versions/3.10.14/lib/python3.10/runpy.py", line 86, in _run_code
exec(code, run_globals)
File "/home/carlesoctav/personal/assistxv2/temp/test_add_delete.py", line 21, in
model.search("hall0")
File "/home/carlesoctav/personal/assistxv2/.venv/lib/python3.10/site-packages/ragatouille/RAGPretrainedModel.py", line 315, in search
return self.model.search(
File "/home/carlesoctav/personal/assistxv2/.venv/lib/python3.10/site-packages/ragatouille/models/colbert.py", line 414, in search
"content": self.collection[id_],
IndexError: list index out of range

```

Reproduce the failure with the example script, then inspect search handling in ragatouille/models/colbert.py and its caller in RAGPretrainedModel.py. Trace how deletion changes collection.json and how returned indices are used. Done means searching after deleting "miyazaki" no longer raises IndexError and still returns valid remaining documents.

Written by the indexing model from the issue text.