Fix exponential search for empty collections

[Dhaylight1]

I’ve confirmed the issue and am formatting the fix summary in the exact PR template you shared so it’s ready to paste into the GitHub description.

Describe your change

• Fix a bug or typo in an existing algorithm?
• Add an algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

This fix addresses a boundary bug in the exponential search implementation in exponential_search.py. The function previously accessed sorted_collection[0] without checking whether the list was empty, which caused an IndexError for empty inputs. The fix adds the required empty-list guard so the function correctly returns -1 when the collection is empty, while preserving the expected behavior for valid sorted inputs.

Checklist

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues, then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

[cclauss]

ON HOLD: Our focus is on merging or closing old pull requests before October 1st.

• https://hacktoberfest.com