Fix crash on plugin reload (#895)

* Update Event.kt

* Update Event.kt

app/src/main/java/com/lagradost/cloudstream3/utils/Event.kt

@@ -3,18 +3,24 @@ package com.lagradost.cloudstream3.utils
 class Event<T> {
     private val observers = mutableSetOf<(T) -> Unit>()
 
-    val size : Int get() = observers.size
+    val size: Int get() = observers.size
 
     operator fun plusAssign(observer: (T) -> Unit) {
-        observers.add(observer)
+        synchronized(observers) {
+            observers.add(observer)
+        }
     }
 
     operator fun minusAssign(observer: (T) -> Unit) {
-        observers.remove(observer)
+        synchronized(observers) {
+            observers.remove(observer)
+        }
     }
 
     operator fun invoke(value: T) {
-        for (observer in observers)
-            observer(value)
+        synchronized(observers) {
+            for (observer in observers)
+                observer(value)
+        }
     }
 }