Fix a ReadConsoleOutputCharacter regression

src/host/output.cpp

@@ -222,7 +222,12 @@ std::wstring ReadOutputStringW(const SCREEN_INFORMATION& screenInfo,
             // Otherwise, add anything that isn't a trailing cell. (Trailings are duplicate copies of the leading.)
             if (it->DbcsAttr() != DbcsAttribute::Trailing)
             {
-                retVal += it->Chars();
+                auto chars = it->Chars();
+                if (chars.size() > 1)
+                {
+                    chars = { &UNICODE_REPLACEMENT, 1 };
+                }
+                retVal += chars;
             }
         }