Fix null managers

[FerroEduardo]

java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:115)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at com.softawii.curupira.core.CommandHandler.execute(CommandHandler.java:104)
	at com.softawii.curupira.core.Curupira.onSlashCommandInteraction(Curupira.java:384)
	at net.dv8tion.jda.api.hooks.ListenerAdapter.onEvent(ListenerAdapter.java:446)
	at net.dv8tion.jda.api.hooks.InterfacedEventManager.handle(InterfacedEventManager.java:96)
	at net.dv8tion.jda.internal.hooks.EventManagerProxy.handleInternally(EventManagerProxy.java:88)
	at net.dv8tion.jda.internal.hooks.EventManagerProxy.handle(EventManagerProxy.java:70)
	at net.dv8tion.jda.internal.JDAImpl.handleEvent(JDAImpl.java:177)
	at net.dv8tion.jda.internal.handle.InteractionCreateHandler.handleCommand(InteractionCreateHandler.java:112)
	at net.dv8tion.jda.internal.handle.InteractionCreateHandler.handleInternally(InteractionCreateHandler.java:83)
	at net.dv8tion.jda.internal.handle.SocketHandler.handle(SocketHandler.java:39)
	at net.dv8tion.jda.internal.requests.WebSocketClient.onDispatch(WebSocketClient.java:1015)
	at net.dv8tion.jda.internal.requests.WebSocketClient.onEvent(WebSocketClient.java:901)
	at net.dv8tion.jda.internal.requests.WebSocketClient.handleEvent(WebSocketClient.java:879)
	at net.dv8tion.jda.internal.requests.WebSocketClient.onBinaryMessage(WebSocketClient.java:1054)
	at com.neovisionaries.ws.client.ListenerManager.callOnBinaryMessage(ListenerManager.java:385)
	at com.neovisionaries.ws.client.ReadingThread.callOnBinaryMessage(ReadingThread.java:276)
	at com.neovisionaries.ws.client.ReadingThread.handleBinaryFrame(ReadingThread.java:996)
	at com.neovisionaries.ws.client.ReadingThread.handleFrame(ReadingThread.java:755)
	at com.neovisionaries.ws.client.ReadingThread.main(ReadingThread.java:108)
	at com.neovisionaries.ws.client.ReadingThread.runMain(ReadingThread.java:64)
	at com.neovisionaries.ws.client.WebSocketThread.run(WebSocketThread.java:45)
Caused by: java.lang.NullPointerException: Cannot invoke "com.softawii.capivara.core.EmbedManager.init()" because "com.softawii.capivara.listeners.EchoGroup.embedManager" is null
	at com.softawii.capivara.listeners.EchoGroup.echo(EchoGroup.java:93)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	... 22 more