[MIRROR] Shuffles around the reagent scan readout to display as empty when only invisible reagents are present [MDB IGNORE] (#19033)

Shuffles around the reagent scan readout to display as empty when only invisible reagents are present (#72915)

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## About The Pull Request

Formerly, the reagent scan would provide a header based on whether or
not reagents are present in a person's blood/stomach. This works, until
you get cases where a user only has invisible reagents in their system,
in which case the "Subject contains the following reagents" header would
appear, but no chemical readouts would be present.

The blood/stomach reagent readouts on the scanner now put their contents
into a separate list, before adding it to the master readout list. This
alternate list is checked for length, rather than whether or not the
user has any reagents in their system at all, to determine what readout
header to give. If there are no reagent readouts to provide, the scanner
will report as if there is nothing present.

In summary: If you have only invisible reagents in your system, the
health scanner will provide the same readout as if you had nothing in
you at all.

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## Why It's Good For The Game

Closes #72311.

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## Changelog

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🆑 Rhials
fix: The chemical scanner will now properly display that "no" reagents
are present in a subject when only invisible reagents are present.
/🆑

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Co-authored-by: Rhials <Datguy33456@gmail.com>

code/game/objects/items/devices/scanners/health_analyzer.dm

@@ -395,36 +395,44 @@
 		return
 
 	if(istype(target) && target.reagents)
-		var/render_list = list()
+		var/list/render_list = list() //The master list of readouts, including reagents in the blood/stomach, addictions, quirks, etc.
+		var/list/render_block = list() //A second block of readout strings. If this ends up empty after checking stomach/blood contents, we give the "empty" header.
 
 		// Blood reagents
 		if(target.reagents.reagent_list.len)
-			render_list += "<span class='notice ml-1'>Subject contains the following reagents in their blood:</span>\n"
 			for(var/r in target.reagents.reagent_list)
 				var/datum/reagent/reagent = r
 				if(reagent.chemical_flags & REAGENT_INVISIBLE) //Don't show hidden chems on scanners
 					continue
-				render_list += "<span class='notice ml-2'>[round(reagent.volume, 0.001)] units of [reagent.name][reagent.overdosed ? "</span> - [span_boldannounce("OVERDOSING")]" : ".</span>"]\n"
-		else
+				render_block += "<span class='notice ml-2'>[round(reagent.volume, 0.001)] units of [reagent.name][reagent.overdosed ? "</span> - [span_boldannounce("OVERDOSING")]" : ".</span>"]\n"
+
+		if(!length(render_block)) //If no VISIBLY DISPLAYED reagents are present, we report as if there is nothing.
 			render_list += "<span class='notice ml-1'>Subject contains no reagents in their blood.</span>\n"
+		else
+			render_list += "<span class='notice ml-1'>Subject contains the following reagents in their blood:</span>\n"
+			render_list += render_block //Otherwise, we add the header, reagent readouts, and clear the readout block for use on the stomach.
+			render_block.Cut()
 
 		// Stomach reagents
 		var/obj/item/organ/internal/stomach/belly = target.getorganslot(ORGAN_SLOT_STOMACH)
 		if(belly)
 			if(belly.reagents.reagent_list.len)
-				render_list += "<span class='notice ml-1'>Subject contains the following reagents in their stomach:</span>\n"
 				for(var/bile in belly.reagents.reagent_list)
 					var/datum/reagent/bit = bile
-					if(bit.chemical_flags & REAGENT_INVISIBLE) //Don't show hidden chems on scanners
+					if(bit.chemical_flags & REAGENT_INVISIBLE)
 						continue
 					if(!belly.food_reagents[bit.type])
-						render_list += "<span class='notice ml-2'>[round(bit.volume, 0.001)] units of [bit.name][bit.overdosed ? "</span> - [span_boldannounce("OVERDOSING")]" : ".</span>"]\n"
+						render_block += "<span class='notice ml-2'>[round(bit.volume, 0.001)] units of [bit.name][bit.overdosed ? "</span> - [span_boldannounce("OVERDOSING")]" : ".</span>"]\n"
 					else
 						var/bit_vol = bit.volume - belly.food_reagents[bit.type]
 						if(bit_vol > 0)
-							render_list += "<span class='notice ml-2'>[round(bit_vol, 0.001)] units of [bit.name][bit.overdosed ? "</span> - [span_boldannounce("OVERDOSING")]" : ".</span>"]\n"
-			else
+							render_block += "<span class='notice ml-2'>[round(bit_vol, 0.001)] units of [bit.name][bit.overdosed ? "</span> - [span_boldannounce("OVERDOSING")]" : ".</span>"]\n"
+
+			if(!length(render_block))
 				render_list += "<span class='notice ml-1'>Subject contains no reagents in their stomach.</span>\n"
+			else
+				render_list += "<span class='notice ml-1'>Subject contains the following reagents in their stomach:</span>\n"
+				render_list += render_block
 
 		// Addictions
 		if(LAZYLEN(target.mind?.active_addictions))