Improve compile with optimizations

Plugin/Templates/server.pb.swift

@@ -115,7 +115,7 @@ import SwiftProtobuf
   /// Start the server.
   {{ access }} func start(queue:DispatchQueue = DispatchQueue.global()) {
     guard let provider = self.provider else {
-      assert(false) // the server requires a provider
+      fatalError() // the server requires a provider
     }
     server.run {(handler) in
       print("Server received request to " + handler.host