Make string::split(s, "") throw Exception.

include/string.hpp

@@ -74,7 +74,7 @@ Examples:
 	split("abc", "+") // {"abc"}
 	split("a++c", "+") // {"a", "", "c"}
 	split("", "+") // {}
-	split("abc", "") // {"a", "b", "c"}
+	split("abc", "") // throws rack::Exception
 */
 std::vector<std::string> split(const std::string& s, const std::string& seperator);
 

src/string.cpp

@@ -206,20 +206,13 @@ bool CaseInsensitiveCompare::operator()(const std::string& a, const std::string&
 
 
 std::vector<std::string> split(const std::string& s, const std::string& separator) {
+	if (separator.empty())
+		throw Exception("split(): separator cannot be empty string");
 	// Special case of empty string
 	if (s == "")
 		return {};
 
 	std::vector<std::string> v;
-	// Special case of empty separator
-	if (separator == "") {
-		for (char c : s) {
-			std::string token(1, c);
-			v.push_back(token);
-		}
-		return v;
-	}
-
 	size_t sepLen = separator.size();
 	size_t start = 0;
 	size_t end;