fix(searches): handle empty list in exponential_search

Fixes IndexError when sorted_collection is empty by
returning -1 early before accessing index 0.

Author: deepshekhardas

searches/exponential_search.py

@@ -85,6 +85,9 @@ def exponential_search(sorted_collection: list[int], item: int) -> int:
     if list(sorted_collection) != sorted(sorted_collection):
         raise ValueError("sorted_collection must be sorted in ascending order")
 
+    if not sorted_collection:
+        return -1
+
     if sorted_collection[0] == item:
         return 0