Here are some issues with the partition flag when using a configuration file:

• Invalid partition flags cause a crash with a KeyError
• Partition flags are case-sensitive; "Boot" is valid but "boot" is not
• "XBOOTLDR" is valid but "bls_boot" is not

Since partition flags are derived from parted it is preferable to accept flags (that are supported by archinstall) as shown in the parted documentation. Partition flags should be case-insensitive to support backwards compatibility. When an invalid flag is encountered it should be logged rather than crash.