Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32l4/STM32L412/FLASH/ECCR#0x0
Flash ECC register
ECC fail address
ECC fail bank
System Flash ECC fail
ECC correction interrupt enable
ECC correction
ECC detection
https://github.com/modm-io/cmsis-svd-stm32