Invalid library found

Invalid library found in C:\Users\nate8\AppData\Local\Arduino15\packages\Seeeduino\hardware\mbed\2.9.0\libraries\Spi_Flash: no headers files (.h) found in C:\Users\nate8\AppData\Local\Arduino15\packages\Seeeduino\hardware\mbed\2.9.0\libraries\Spi_Flash

Have you progressed on this error, I suddenly have the same error?

From Boards Manager Select
Seeed nRF52840 mbed-enabled Boards by Seed Studio

In Preferences > Additional boards manager Urls> Cleared everything and select https://files.seeedstudio.com/arduino/package_seeeduino_boards_index.json

From Tools>
COM??? (Seeed Xiao BLE - nRF52840, Seeed Xiao BLE Sense - nRF52840)

Worked for me.
Good Luck