diagnose throw_hresult(success_code) better (#689)

Author: oldnewthing

strings/base_error.h

@@ -183,17 +183,17 @@ WINRT_EXPORT namespace winrt
             return *this;
         }
 
-        explicit hresult_error(hresult const code) noexcept : m_code(code)
+        explicit hresult_error(hresult const code) noexcept : m_code(verify_error(code))
         {
             originate(code, nullptr);
         }
 
-        hresult_error(hresult const code, param::hstring const& message) noexcept : m_code(code)
+        hresult_error(hresult const code, param::hstring const& message) noexcept : m_code(verify_error(code))
         {
             originate(code, get_abi(message));
         }
 
-        hresult_error(hresult const code, take_ownership_from_abi_t) noexcept : m_code(code)
+        hresult_error(hresult const code, take_ownership_from_abi_t) noexcept : m_code(verify_error(code))
         {
             com_ptr<impl::IErrorInfo> info;
             WINRT_IMPL_GetErrorInfo(0, info.put_void());
@@ -306,6 +306,13 @@ WINRT_EXPORT namespace winrt
             WINRT_VERIFY(info.try_as(m_info));
         }
 
+        static hresult verify_error(hresult const code) noexcept
+        {
+            WINRT_ASSERT(code < 0);
+            return code;
+        }
+
+
 #ifdef __clang__
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wunused-private-field"