fix: reject empty negative binary input

Author: Yash4305d-y

conversions/binary_to_decimal.py

@@ -18,6 +18,14 @@ def bin_to_decimal(bin_string: str) -> int:
     Traceback (most recent call last):
         ...
     ValueError: Empty string was passed to the function
+    >>> bin_to_decimal("-")
+    Traceback (most recent call last):
+        ...
+    ValueError: Non-binary value was passed to the function
+    >>> bin_to_decimal(" - ")
+    Traceback (most recent call last):
+        ...
+    ValueError: Non-binary value was passed to the function
     >>> bin_to_decimal("39")
     Traceback (most recent call last):
         ...
@@ -29,7 +37,7 @@ def bin_to_decimal(bin_string: str) -> int:
     is_negative = bin_string[0] == "-"
     if is_negative:
         bin_string = bin_string[1:]
-    if not all(char in "01" for char in bin_string):
+    if not bin_string or not all(char in "01" for char in bin_string):
         raise ValueError("Non-binary value was passed to the function")
     decimal_number = 0
     for char in bin_string: