Fixes various runtimes (#8702)

* Fixes runtime:

type mismatch: "30" -= 0
proc name: playsound to (/mob/proc/playsound_to)

* Fixes runtime:

Cannot read null.name
proc name: Toggle Underwear (/mob/living/carbon/human/verb/toggle_underwear)

* Fixes runtime:

invalid view size
proc name: get mobs and objs in view fast (/proc/get_mobs_and_objs_in_view_fast)

code/game/machinery/kitchen/microwave.dm

@@ -11,7 +11,7 @@
 	active_power_usage = 2000
 	flags = OPENCONTAINER | NOREACT
 	clicksound = "button"
-	clickvol = "30"
+	clickvol = 30
 
 	var/operating = FALSE // Is it on?
 	var/dirty = 0 // = {0..100} Does it need cleaning?

code/modules/mob/living/carbon/human/human.dm

@@ -1778,6 +1778,8 @@
 	if(stat)
 		return
 	var/datum/category_group/underwear/UWC = input(usr, "Choose underwear:", "Show/hide underwear") as null|anything in global_underwear.categories
+	if(!UWC)
+		return
 	var/datum/category_item/underwear/UWI = all_underwear[UWC.name]
 	if(!UWI || UWI.name == "None")
 		to_chat(src, "<span class='notice'>You do not have [UWC.gender==PLURAL ? "[UWC.display_name]" : "any [UWC.display_name]"].</span>")

code/modules/modular_computers/computers/modular_computer/interaction.dm

@@ -174,7 +174,7 @@
 		playsound(user, W.usesound, 100, 1)
 		if (do_after(user, 20/W.toolspeed))
 			new /obj/item/stack/material/steel(get_turf(src.loc), steel_sheet_cost)
-			src.visible_message("\The [user] disassembles \the [src].",
+			user.visible_message("\The [user] disassembles \the [src].",
 				"You disassemble \the [src].",
 				"You hear a ratchet.")
 			qdel(src)