fix(JitsiConnectionErrors): split "dropped" from "other" error type

JitsiConnectionErrors.js

  * The errors for the connection.
  */
 
+/**
+ * Indicates that the connection was dropped with an error which was most likely
+ * caused by some networking issues. The dropped term in this context means that
+ * the connection was closed unexpectedly (not on user's request).
+ *
+ * One example is 'item-not-found' error thrown by Prosody when the BOSH session
+ * times out after 60 seconds of inactivity. On the other hand 'item-not-found'
+ * could also happen when BOSH request is sent to the server with the session-id
+ * that is not know to the server. But this should not happen in lib-jitsi-meet
+ * case as long as the service is configured correctly (there is no bug).
+ */
+export const CONNECTION_DROPPED_ERROR = "connection.droppedError";
 /**
  * Indicates that a connection error occurred when trying to join a conference.
  */

modules/xmpp/xmpp.js

                 } else {
                     this.eventEmitter.emit(
                         JitsiConnectionEvents.CONNECTION_FAILED,
-                        JitsiConnectionErrors.OTHER_ERROR,
+                        JitsiConnectionErrors.CONNECTION_DROPPED_ERROR,
                         errMsg ? errMsg : 'connection-dropped-error');
                 }
             } else {