Deal with total people suffix (#2)

Co-authored-by: Smaug123 <patrick+github@patrickstevens.co.uk>
Reviewed-on: #2

PureGym/Api.fs

@@ -177,6 +177,7 @@ type GymAttendance =
         /// How many people are in classes at the gym as of this statistics snapshot
         [<JsonRequired>]
         TotalPeopleInClasses : int
+        /// E.g. " or fewer"
         TotalPeopleSuffix : string
         [<JsonRequired>]
         IsApproximate : bool
@@ -192,8 +193,10 @@ type GymAttendance =
 
     /// Human-readable representation
     override this.ToString () =
-        if not (Object.ReferenceEquals (this.TotalPeopleSuffix, null)) then
-            failwith $"Unexpectedly got Total People Suffix: %s{this.TotalPeopleSuffix}"
+        let totalPeopleSuffix =
+            match this.TotalPeopleSuffix with
+            | null -> ""
+            | suffix -> suffix
 
         let capacity =
             if this.MaximumCapacity = 0 then
@@ -207,7 +210,7 @@ type GymAttendance =
             else
                 $"\n%i{this.TotalPeopleInClasses} in classes"
 
-        $"""%i{this.TotalPeopleInGym} in gym%s{capacity} (is exact: %c{Char.emoji (not this.IsApproximate)})%s{classes}
+        $"""%i{this.TotalPeopleInGym}%s{totalPeopleSuffix} in gym%s{capacity} (is exact: %c{Char.emoji (not this.IsApproximate)})%s{classes}
 Query made at %s{this.AttendanceTime.ToString "s"}%s{this.AttendanceTime.ToString "zzz"}
 Snapshot correct as of %s{this.LastRefreshed.ToString "s"}%s{this.LastRefreshed.ToString "zzz"}
 Classes info correct as of %s{this.LastRefreshedPeopleInClasses.ToString "s"}%s{this.LastRefreshedPeopleInClasses.ToString "zzz"}"""