Thread Crash XMLFeedParser Line 88 Unexpectedly found nil while unwrapping an Optional value

[neilt]

* thread #37, queue = 'com.apple.root.user-initiated-qos', stop reason = Fatal error: Unexpectedly found nil while unwrapping an Optional value
    frame #0: 0x00007fff64e2cd50 libswiftCore.dylib`_swift_runtime_on_report
    frame #1: 0x00007fff64e8c788 libswiftCore.dylib`_swift_stdlib_reportFatalError + 168
    frame #2: 0x00007fff64d8d106 libswiftCore.dylib`function signature specialization <Arg[0] = Exploded, Arg[1] = Exploded> of closure #2 (Swift.UnsafeBufferPointer<Swift.UInt8>) -> () in Swift._fatalErrorMessage(_: Swift.StaticString, _: Swift.StaticString, file: Swift.StaticString, line: Swift.UInt, flags: Swift.UInt32) -> Swift.Never + 70
    frame #3: 0x00007fff64d8d483 libswiftCore.dylib`function signature specialization <Arg[0] = Exploded, Arg[1] = Exploded, Arg[2] = Dead, Arg[3] = Dead> of Swift._fatalErrorMessage(_: Swift.StaticString, _: Swift.StaticString, file: Swift.StaticString, line: Swift.UInt, flags: Swift.UInt32) -> Swift.Never + 307
    frame #4: 0x00007fff64b8ca03 libswiftCore.dylib`Swift._fatalErrorMessage(_: Swift.StaticString, _: Swift.StaticString, file: Swift.StaticString, line: Swift.UInt, flags: Swift.UInt32) -> Swift.Never + 19
  * frame #5: 0x0000000100146bf5 RSS2PGGatherer`XMLFeedParser.parse(self=0x0000000119585800) at XMLFeedParser.swift:88:56
    frame #6: 0x0000000100147e63 RSS2PGGatherer`protocol witness for FeedParserProtocol.parse() in conformance XMLFeedParser at <compiler-generated>:0
    frame #7: 0x00000001000a1532 
RSS2PGGatherer`FeedParser.parse(self=0x0000000102225ce0) at FeedParser.swift:88:28
    frame #8: 0x00000001000a2922 RSS2PGGatherer`closure #1 in FeedParser.parseAsync(result=0x0000000100051620 RSS2PGGatherer`partial apply forwarder for closure #1 (FeedKit.Result) -> () in RSS2PGGatherer.RSSFeedRetrieval.retrieve(completionHandler: (Foundation.URL) -> (), errorHandler: (Swift.String) -> ()) -> () at <compiler-generated>, self=0x0000000102225ce0) at FeedParser.swift:118:25
    frame #9: 0x00000001000a29c5 RSS2PGGatherer`partial apply for closure #1 in FeedParser.parseAsync(queue:result:) at <compiler-generated>:0
    frame #10: 0x000000010004816d RSS2PGGatherer`thunk for @escaping @callee_guaranteed () -> () at <compiler-generated>:0
    frame #11: 0x00000001009dbe7c libdispatch.dylib`_dispatch_call_block_and_release + 12
    frame #12: 0x00000001009dcf1b libdispatch.dylib`_dispatch_client_callout + 8
    frame #13: 0x00000001009efa06 libdispatch.dylib`_dispatch_root_queue_drain + 816
    frame #14: 0x00000001009f02da libdispatch.dylib`_dispatch_worker_thread2 + 125
    frame #15: 0x0000000100a560b7 libsystem_pthread.dylib`_pthread_wqthread + 583
    frame #16: 0x0000000100a55e01 libsystem_pthread.dylib`start_wqthread + 13

XMLFeedParser line 88.

(lldb) po self.rssFeed
nil

(lldb) po self.atomFeed
nil

(lldb) po self.data
▿ Optional<Data>
  ▿ some : 21 bytes
    - count : 21
    ▿ pointer : 0x00000001195550e0
      - pointerValue : 4719988960
    ▿ bytes : 21 elements
      - 0 : 60
      - 1 : 114
      - 2 : 115
      - 3 : 115
      - 4 : 32
      - 5 : 118
      - 6 : 101
      - 7 : 114
      - 8 : 115
      - 9 : 105
      - 10 : 111
      - 11 : 110
      - 12 : 61
      - 13 : 34
      - 14 : 50
      - 15 : 46
      - 16 : 48
      - 17 : 34
      - 18 : 32
      - 19 : 47
      - 20 : 62
(lldb) po String(data: self.data!, encoding: .utf8)
▿ Optional<String>
  - some : "<rss version=\"2.0\" />"

FeedParser line 117

(lldb) po self.url
▿ Optional<URL>
  ▿ some : http://apps.shareholder.com/rss/rss.aspx?channels=274&companyid=NDAQ
    - _url : http://apps.shareholder.com/rss/rss.aspx?channels=274&companyid=NDAQ

[neilt]

The following code fixes the issue for me. Two potential problems with this code.

1) I did not delve into the error handling code to determine if it was appropriate to use the internal error or if it would have been better to define a new error.

2) The case for .atom appears to potentially have the same problem, but none of my current feeds revealed a problem so I left it alone.

diff --git a/Sources/FeedKit/Parser/XMLFeedParser.swift b/Sources/FeedKit/Parser/XMLFeedParser.swift
index 33b48fc..0597083 100644
--- a/Sources/FeedKit/Parser/XMLFeedParser.swift
+++ b/Sources/FeedKit/Parser/XMLFeedParser.swift
@@ -85,9 +85,15 @@ class XMLFeedParser: NSObject, XMLParserDelegate, FeedParserProtocol {

         switch feedType {
         case .atom: return Result.atom(self.atomFeed!)
-        case .rdf, .rss: return Result.rss(self.rssFeed!)
+        case .rdf, .rss:
+            if let rssFeed = self.rssFeed {
+                return Result.rss(rssFeed)
+            }
+            else {
+                return Result.failure(ParserError.internalError(reason: "No RSS Feed.").value)
+            }
         }
-        
+
     }

     /// Redirects characters found between XML elements to their proper model

[nmdias]

Hi, @neilt

I was unable to replicate, but safeguarding against a possible uninitializel model seems more than reasonable, so the force unwrap was removed and an appropriate result is now returned.

Thanks

[neilt]

Thanks.