Fix start index for component iterators

Sources/FirebladeECS/TypedFamily.swift

@@ -12,12 +12,18 @@ public protocol TypedFamilyProtocol: AnyObject {
     var nexus: Nexus? { get }
     var memberIds: UniformEntityIdentifiers { get }
     var members: Members { get set }
+
+    var count: Int { get }
 }
 
 public extension TypedFamilyProtocol {
     var memberIds: UniformEntityIdentifiers {
         return nexus?.members(withFamilyTraits: traits) ?? UniformEntityIdentifiers()
     }
+
+    var count: Int {
+        return memberIds.count
+    }
 }
 
 public protocol FamilyMembersProtocol: LazySequenceProtocol {

Sources/FirebladeECS/TypedFamily1.swift

@@ -40,12 +40,11 @@ public struct ComponentIterator1<A>: ComponentIteratorProtocol where A: Componen
 
     public private(set) weak var nexus: Nexus?
     public let memberIds: UniformEntityIdentifiers
-    public var index: Int
+    public var index: Int = -1
 
     public init(_ nexus: Nexus?, _ family: TypedFamily1<A>) {
         self.nexus = nexus
         memberIds = family.memberIds
-        index = memberIds.index(before: memberIds.startIndex)
     }
 
     public mutating func next() -> A? {

Sources/FirebladeECS/TypedFamily2.swift

@@ -40,12 +40,11 @@ public struct ComponentIterator2<A, B>: ComponentIteratorProtocol where A: Compo
 
     public private(set) weak var nexus: Nexus?
     public let memberIds: UniformEntityIdentifiers
-    public var index: Int
+    public var index: Int = -1
 
     public init(_ nexus: Nexus?, _ family: TypedFamily2<A, B>) {
         self.nexus = nexus
         memberIds = family.memberIds
-        index = memberIds.index(before: memberIds.startIndex)
     }
 
     public mutating func next() -> (A, B)? {

Sources/FirebladeECS/TypedFamily3.swift

@@ -41,12 +41,11 @@ public struct ComponentIterator3<A, B, C>: ComponentIteratorProtocol where A: Co
 
     public private(set) weak var nexus: Nexus?
     public let memberIds: UniformEntityIdentifiers
-    public var index: Int
+    public var index: Int = -1
 
     public init(_ nexus: Nexus?, _ family: TypedFamily3<A, B, C>) {
         self.nexus = nexus
         memberIds = family.memberIds
-        index = memberIds.index(before: memberIds.startIndex)
     }
 
     public mutating func next() -> (A, B, C)? {

Sources/FirebladeECS/TypedFamily4.swift

@@ -41,12 +41,11 @@ public struct ComponentIterator4<A, B, C, D>: ComponentIteratorProtocol where A:
 
     public private(set) weak var nexus: Nexus?
     public let memberIds: UniformEntityIdentifiers
-    public var index: Int
+    public var index: Int = -1
 
     public init(_ nexus: Nexus?, _ family: TypedFamily4<A, B, C, D>) {
         self.nexus = nexus
         memberIds = family.memberIds
-        index = memberIds.index(before: memberIds.startIndex)
     }
 
     public mutating func next() -> (A, B, C, D)? {

Sources/FirebladeECS/TypedFamily5.swift

@@ -41,12 +41,11 @@ public struct ComponentIterator5<A, B, C, D, E>: ComponentIteratorProtocol where
 
     public private(set) weak var nexus: Nexus?
     public let memberIds: UniformEntityIdentifiers
-    public var index: Int
+    public var index: Int = -1
 
     public init(_ nexus: Nexus?, _ family: TypedFamily5<A, B, C, D, E>) {
         self.nexus = nexus
         memberIds = family.memberIds
-        index = memberIds.index(before: memberIds.startIndex)
     }
 
     public mutating func next() -> (A, B, C, D, E)? {