[bug] Sideloaded service configuration fails if pointers previously existed

[elvece]

After sideloading a service, attempting to configure it if the config had union pointers in 0351 fails with the following error:

The patch payload:

This error does not occur if the same service@version is installed from the marketplace.
Example:

• sideload this btcpay version
• attempt to save config
• see error
• uninstall
• install same version of btcpay from the alpha marketplace
• attempt to configure
• configuration saves successfully

[MattDHill]

Some more context here, as there are multiple possible bugs:

1. installing from alpha and sideloading are producing different behavior.
2. when side loaded, the observed behavior might have nothing to do with pointers, might just be unions in general. Need to test another service with unions to confirm.
3. when installed from alpha, running the action "works", meaning no error is produced, but neither does it result in the expected dependnecies being created. Upon running the action, BTCPay should have dependencies on both Bitcoin an LND/CLN, but neither are created.

[elvece]

This happens 100% of the time when you have a fresh OS image with no services installed and sideload or install btcpay from alpha. If you uninstall btcpay and sideload/ install from alpha it again, the error persists.

If you install bitcoin, configure it, and then configure btcpay, the error is not produced.

so perhaps its only if the first service you try to save is a service that previously had a config union with pointers.