Fix setting a prefix list option with an empty list

Fixes #2335

src/option_types.hh

@@ -350,6 +350,9 @@ inline String option_to_string(const PrefixedList<P, T>& opt, Quoting quoting)
 template<typename P, typename T>
 inline PrefixedList<P, T> option_from_strings(Meta::Type<PrefixedList<P, T>>, ConstArrayView<String> strs)
 {
+    if (strs.empty())
+        return {{}, {}};
+
     return {option_from_string(Meta::Type<P>{}, strs[0]),
             option_from_strings(Meta::Type<Vector<T, MemoryDomain::Options>>{}, strs.subrange(1))};
 }