Fix iOS initial invocation events (Instabug#148)

* Update InstabugFlutterPlugin.m

* Update CHANGELOG.md

Author: Ali Abdelfattah

CHANGELOG.md

@@ -1,3 +1,7 @@
+## master
+
+* Fixes an issue with iOS invocation events causing the welcome message not to show.
+
 ## v9.1.7 (2020-10-01)
 
 * Adds support for the Azerbaijani locale

ios/Classes/InstabugFlutterPlugin.m

@@ -68,10 +68,13 @@ + (void)startWithToken:(NSString *)token invocationEvents:(NSArray*)invocationEv
     }
 
     NSDictionary *constants = [self constants];
-    NSInteger invocationEvents = IBGInvocationEventNone;
+    NSInteger invocationEvents = 0;
     for (NSString * invocationEvent in invocationEventsArray) {
         invocationEvents |= ((NSNumber *) constants[invocationEvent]).integerValue;
     }
+    if (invocationEvents == 0) {
+        invocationEvents = IBGInvocationEventNone;
+    }
     [Instabug startWithToken:token invocationEvents:invocationEvents];
 }