What happens to a Chain lighting with invalid primary target and valid secondary targets?

This question asks what happens when a single-target spell has an invalid target. (A target that is not legitimately permissible, not a target that is weak from illness or injury).

The answer appears to be: that depends on whether one wishes to implement an older Sage Advice segment of a Dragon Talk podcast, or the more recent but optional written rules in Xanathar’s Guide to Everything.

Assume for this question that I prefer XGtE.

The rule for resolving invalid spell targets states (XGtE 85-86):

If you cast a spell on someone or something that can’t be affected by the spell, nothing happens to that target, but if you used a spell slot to cast the spell, the slot is still expended.

Now consider the chain lightning spell, in which

You create a bolt of lightning that arcs toward a target of your choice that you can see within range. Three bolts then leap from that target to as many as three other targets, each of which must be within 30 feet of the first target. A target can be a creature or an object and can be targeted by only one of the bolts.

Suppose my primary target for the spell is invalid, because it is not a creature or an object. If an example must be given, suppose it is an illusion. However, each of the three secondary targets of the spell are valid, being either creatures or objects.

Do I spend the spell slot with nothing happening at all, or does the slot get spent, the chain lightning impact the illusion but do nothing to it and then leap to the three valid targets with the full effects given in the spell description?

Note: I am assuming that an illusion is not an object, based largely on my interpretation that an illusion is not an "item" and on the text of the 14th-level School of Illusion wizard feature, Illusory Reality. I am open to frame challenges that demonstrate that illusions are, in fact, objects, but such answers will be better if they then either provide a more appropriate example of something that is not a creature or an object, or demonstrate that the question is moot since everything is at least either a creature or an object.

Hexblade’s Curse + Booming Blade’s secondary damage

While trying to minmax a build for a Bladesinger by way of the new TCoE book I happened upon a curious problem with which I need assistance. The bonus damage from Hexblade’s Curse reads

[…] You gain a bonus to damage rolls against the cursed target. The bonus equals your proficiency bonus.

So my question can be summed up as ‘What constitutes a separate damage roll?’ Are damage rolls separated by source? Perhaps by damage type? Are they separated by when the damage is dealt?

For example…

A creature is struck by a Bladesinger/Hexblade using the special Extra Attack feature in Tasha’s Cauldron of Everything; once using a 7th level Shadow Blade, and once using Booming Blade. The creature is under the effects of Hexblade’s Curse.

How is the damage calculated? Is the Hexblade’s curse damage applied to the initial strike, the second strike, and the damage the creature takes when it moves? Or is the curse damage ignored when the creature moves since the source of that damage has already dealt the curse damage?

Does standing up from prone trigger the secondary damage from the Booming Blade cantrip?

Does spending movement to stand up from prone trigger the secondary damage effect of the booming blade spell from the Sword Coast Adventurer’s Guide (p. 142)? The spell says:

If the target willingly moves before the duration expires, it immediately takes 1d8 thunder damage, and the spell ends.

Primary index vs clustered vs non clustered vs secondary index

I am new to ETL testing and dB environment.Some say PI is clustered index some say it is not. Even I found some where that secondary index is non clustered index. What is actually primary index and secondary index? When do we need primary index and when we need secondary index? If PI index and clustered index are different then how are they different?

Does a country code secondary domain (such as .com.nl) have lower ranking than a ccTLD (such as .nl) with content specific for that country?

I know that search engines like Google value more country code top level domains (ccTLD) on content that is specific to residents living in said countries, that is, the website hosted at voorbeeld.nl and whose content is specific for Dutch visitors has a higher rank than voorbeeld.com

And what about voorbeeld.com.nl? Does this example is negatively affected in contrast to voorbeeld.nl?

Wamp Server Secondary Folder

I have an Apache Web Server running with Wamp 64bit on Windows 7, and I wanted to know if there is any way to add a secondary Serve folder on another Drive using the same port but as a subfolder like http://127.0.0.1/public with DocumentRoot S:/public while the first one is on the default C:/wamp64/www

I can’t find anything useful online, so I dont know where to start

Best way to indicate secondary list items within an expandable list will lead to a new screen? iOS mobile app

I’m designing a page with an accordion list (not a sidebar menu) in a financial iOS app. I’m trying show that eacg primary list item is expandable/collapsible (indicated by up-down chevrons), and that secondary items within each primary list item will lead to a new page (indicated by right chevrons).

This is what the list looks like collapsed: List Collapsed

And expanded:

List Expanded

Is having a mix of so many chevrons confusing and cluttered? What’s the clearest way to display this?