5.6.0 - Changing Text in new UI tools via script

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class Click : MonoBehaviour
{
public Text showCoins;
public float coin=0;
public int coinperclick=1;
void Update ()
{
showCoins.text = "Coins: " + coin.ToString();
}
public void click()
{
coin = coin + coinperclick;
}
}

Give me these error:

“Assertion failed on expression: ‘m_CurrentEntriesPtr != NULL && m_IsGettingEntries’
UnityEditorInternal.LogEntries:GetEntryInternal(Int32, LogEntry)
UnityEditor.DockArea:OnGUI()”

Can someone help me solve these error?

It seems you had typed showCoins.Text and not showCoins.text.
Anyway, you may also need to add .ToString() to your float.

showCoins.text = "Coins: " + coin.ToString();