Add numlock set error + handle 2 more errors

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/config/Lang.zig

@@ -14,6 +14,7 @@ err_envlist: []const u8 = "failed to get envlist",
 err_hostname: []const u8 = "failed to get hostname",
 err_mlock: []const u8 = "failed to lock password memory",
 err_null: []const u8 = "null pointer",
+err_numlock: []const u8 = "failed to set numlock",
 err_pam: []const u8 = "pam transaction failed",
 err_pam_abort: []const u8 = "pam transaction aborted",
 err_pam_acct_expired: []const u8 = "account expired",