Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
Usually when I see this error (vFlashErase) it is because some of the falsh areas are write, pcrop, and/or rop protected.
I would recommend looking at the options bytes in ST-Link Utility (ctrl+b).