Fix construction of std::string

Author: StableAgOH

src/cpp/subprocess/utf8_to_utf16.cpp

@@ -118,7 +118,7 @@ namespace subprocess {
         int r = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS,
             string.c_str(), size, NULL, 0);
         if (r == 0) {
-            return std::u16string();
+            return {};
         }
         assert(r > 0);
 
@@ -157,7 +157,7 @@ namespace subprocess {
             (wchar_t*)wstring.c_str(), size, NULL, 0, NULL, NULL);
 
         if (r == 0) {
-            return "";
+            return {};
         }
         assert(r > 0);
 
@@ -191,7 +191,7 @@ namespace subprocess {
             (wchar_t*)wstring.c_str(), size, NULL, 0, NULL, NULL);
 
         if (r == 0) {
-            return "";
+            return {};
         }
         assert(r > 0);