Error handling and debugging

[subtle4553]

Over time I had some cases where feeds couldn't be generated because there's some sort of error for one reason or another. But it seems that RSS bridge doesn't handle errors in a meaningful way. Instead I get new feed items in my reader that display the error and a stack trace. Then I noticed that thrown errors get treated like any other return value in general which doesn't seem right.

Not only do I not see a point in generating a feed if there's an error, it also makes debugging kind of difficult. So, IMO it makes more sense if requesting a feed with an error actually sends a 4xx/5xx status code to the requesting client. I think some clients can list feeds that don't return a 2xx/3xx status code, so it'd also be easy to find broken feeds.

Also, thrown errors could be displayed on the feed preview page (on a page with this URL pattern: ?action=display&bridge=SomeBridge) instead of potential feed entries. That would also make it easier to debug bridges while working on them. If I want to know the value of a variable, I could just throw it, refresh the page and there it is. Currently I have to create a dummy feed to output something. But that would also send it to potential rss readers which I wouldn't want - also because many readers don't support deleting individual items which results in a messy feed.

One neat way to handle different errors would be to introduce some exception classes that get handled accordingly. Like: InvalidInputException if one of the inputs has an unexpected format, which would send a 400 status code, and FeedException if a feed cannot be created successfully, which would send a 500 status code. Any other Exception and Error should do something similar.

Now, how could debugging values work? I'm not sure if there should be something like a DebugException. It might make more sense if debugging was handled via a return value that's different from the return value that creates a feed (EDIT: I forgot, it's not a return value but a property on the bridge class. But there could be a debug property that's null by default and its value could be displayed if it's not null.). But exceptions make debugging values e.g. inside callback functions easier. And I think it'd also be a little easier to implement it through an exception. (EDIT: That actually not try anymore for class properties)

What do you think about this?

[dvikan]

in config, you can change how errors are handled.

default is to emit errors as a feed item.

you can change this to make it return http 500 instead:

see:

[error]

; Defines how error messages are returned by RSS-Bridge
;
; "feed" = As part of the feed (default)
; "http" = As HTTP error message
; "none" = No errors are reported
output = "feed"

please report back if this helps