Try not to swallow exceptions while subscribing

If the query can't be encoded (or any other checked or unchecked Exception
occurs), the async SubscribeClientOperation will swallow the exception,
leaving no way (even a log message) to see why it failed.

This creates a new LiveQueryException subclass (UnknownException) to
represent an unexpected RuntimeException that can then be handled by the
HandleErrorCallback#onError() callback.

Author: Joe Hansche

ParseLiveQuery/src/main/java/com/parse/LiveQueryException.java

@@ -10,6 +10,23 @@ private LiveQueryException(String detailMessage) {
         super(detailMessage);
     }
 
+    private LiveQueryException(String detailMessage, Throwable cause) {
+        super(detailMessage, cause);
+    }
+
+    private LiveQueryException(Throwable cause) {
+        super(cause);
+    }
+
+    /**
+     * An error that is reported when any other unknown {@link RuntimeException} occurs unexpectedly.
+     */
+    public static class UnknownException extends LiveQueryException {
+        /* package */ UnknownException(String detailMessage, RuntimeException cause) {
+            super(detailMessage, cause);
+        }
+    }
+
     /**
      * An error that is reported when the server returns a response that cannot be parsed.
      */

ParseLiveQuery/src/main/java/com/parse/ParseLiveQueryClientImpl.java

@@ -223,8 +223,21 @@ private Subscription<T> subscriptionForRequestId(int requestId) {
         return subscriptions.get(requestId);
     }
 
-    private void sendSubscription(Subscription<T> subscription) {
-        sendOperationAsync(new SubscribeClientOperation<>(subscription.getRequestId(), subscription.getQueryState()));
+    private void sendSubscription(final Subscription<T> subscription) {
+        SubscribeClientOperation<T> op = new SubscribeClientOperation<>(subscription.getRequestId(), subscription.getQueryState());
+        // dispatch errors
+        sendOperationAsync(op).continueWith(new Continuation<Void, Void>() {
+            public Void then(Task<Void> task) {
+                Exception error = task.getError();
+                if (error != null) {
+                    if (error instanceof RuntimeException) {
+                        subscription.didEncounter(new LiveQueryException.UnknownException(
+                                "Error when subscribing", (RuntimeException) error), subscription.getQuery());
+                    }
+                }
+                return null;
+            }
+        });
     }
 
     private void sendUnsubscription(Subscription subscription) {