Review nits

Author: glbrntt

Sources/AsyncHTTPClient/ConnectionPool/State Machine/HTTPConnectionPool+HTTP2Connections.swift

@@ -192,6 +192,7 @@ extension HTTPConnectionPool {
             case .active(let conn, let maxStreams, var usedStreams, let lastIdle, let remainingUses):
                 usedStreams += count
                 precondition(usedStreams <= maxStreams, "tried to lease a connection which is not available")
+                precondition(remainingUses.map { $0 >= count } ?? true, "tried to lease streams from a connection which does not have enough remaining streams")
                 self.state = .active(conn, maxStreams: maxStreams, usedStreams: usedStreams, lastIdle: lastIdle, remainingUses: remainingUses.map { $0 - count })
                 return conn
             }

Sources/AsyncHTTPClient/HTTPClient.swift

@@ -764,8 +764,8 @@ public class HTTPClient {
         /// - Precondition: The value must be greater than zero.
         public var maximumUsesPerConnection: Int? {
             willSet {
-                if let newValue = newValue {
-                    precondition(newValue > 0, "maximumUsesPerConnection must be greater than zero or nil")
+                if let newValue = newValue, newValue <= 0 {
+                    fatalError("maximumUsesPerConnection must be greater than zero or nil")
                 }
             }
         }