Sometimes, seemingly useless items appear when searching in GNOME shell. In order to find out what they are, you have to have a good idea of the search provider--that is, the program providing the search result.
In this case, we see an "Untitled Document" result when searching for pav, a result provided by GNOME Documents. Clicking the search result has never actually resulted in Documents displaying the result, in my experience. Some day I'll file a bug about this, but in the mean time, let's work out which document is responsible.
The GetInitialResultSet method expects an array of strings; these are presumably the search terms. Calling the method with a single string gives us a single result:
$ busctl --user call org.gnome.Documents /org/gnome/Documents/SearchProvider org.gnome.Shell.SearchProvider2 GetInitialResultSet as 1 pav as 1 "urn:uuid:47fa6454-d109-f6d4-a7f3-16cec03e9885" $ tracker info urn:uuid:47fa6454-d109-f6d4-a7f3-16cec03e9885 Querying information for entity:'urn:uuid:47fa6454-d109-f6d4-a7f3-16cec03e9885' Results: 'http://purl.org/dc/elements/1.1/date' = '2013-06-03T16:55:38Z' 'http://purl.org/dc/elements/1.1/date' = '2014-08-21T08:23:20Z' 'http://purl.org/dc/elements/1.1/format' = 'application/pdf' 'http://purl.org/dc/elements/1.1/source' = 'http://www.tracker-project.org/ontologies/tracker#extractor-data-source' 'http://purl.org/dc/elements/1.1/source' = 'urn:nepomuk:datasource:9291a450-1d49-11de-8c30-0800200c9a66' 'tracker:added' = '2017-10-02T10:08:45Z' 'tracker:modified' = '1330' 'rdf:type' = 'http://www.w3.org/2000/01/rdf-schema#Resource' 'rdf:type' = 'http://www.semanticdesktop.org/ontologies/2007/01/19/nie#DataObject' 'rdf:type' = 'http://www.semanticdesktop.org/ontologies/2007/01/19/nie#InformationElement' 'rdf:type' = 'http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#Document' 'rdf:type' = 'http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#FileDataObject' 'rdf:type' = 'http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#TextDocument' 'rdf:type' = 'http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#PaginatedTextDocument' 'nie:byteSize' = '275838' 'nie:dataSource' = 'http://www.tracker-project.org/ontologies/tracker#extractor-data-source' 'nie:dataSource' = 'urn:nepomuk:datasource:9291a450-1d49-11de-8c30-0800200c9a66' 'nie:isPartOf' = 'urn:uuid:27f6d8cd-6b05-2b9e-6670-7b8396fd2f83' 'nie:url' = 'file:///home/sam/ownCloud/_path_redacted_.pdf' 'nfo:belongsToContainer' = 'urn:uuid:27f6d8cd-6b05-2b9e-6670-7b8396fd2f83' 'tracker:available' = 'true' 'maemo:relevance' = '0.0' 'nie:contentCreated' = '2013-06-03T16:55:38Z' 'nie:informationElementDate' = '2013-06-03T16:55:38Z' 'nie:isStoredAs' = 'urn:uuid:47fa6454-d109-f6d4-a7f3-16cec03e9885' 'nie:mimeType' = 'application/pdf' 'nfo:tableOfContents' = 'Cover Table of Contents Introduction Section 1: _text_redacted_' 'nfo:fileLastAccessed' = '2014-08-21T08:23:20Z' 'nfo:fileLastModified' = '2014-08-21T08:23:20Z' 'nfo:fileName' = '_filename_redacted_.pdf' 'nfo:fileSize' = '275838' 'nfo:pageCount' = '34'
There is no mention of "Untitled" in the metadata, but Evince displays the document's title as None, so presumably this PDF is simply missing the metadata. This seems rather common and I think Documents should display something else in this case, like at least the file name!