Error: Could not find file in 'getValidSourceFile' during 'occurrences'

[aozgaa]

This issue comes from crash dumps in telemetry. We've tried to de-duplicate issues on a best-effort basis, comparing the sequence of methods called and the command requested while ignoring line numbers.
TypeScript Version Prefix: 2.7.1
VSCode Version 1.20.0-insider
command requested: occurrences
hitting sessions: 1398
proportion of all sessions: 0.005218891041650334
five line hash: 0c6b87bc0e783daa2cc6e2e55e34e735
stack

Error: Could not find file
    at getValidSourceFile (tsserver.js:82737:23)
    at getDocumentHighlights (tsserver.js:82972:30)
    at getOccurrencesAtPositionCore (tsserver.js:82976:46)
    at Object.getOccurrencesAtPosition (tsserver.js:82962:27)
    at IOSession.Session.getOccurrences (tsserver.js:89496:64)
    at Session.handlers.ts.createMapFromTemplate._a.(anonymous function) (tsserver.js:89112:61)
    at unknown (tsserver.js:90393:88)
    at IOSession.Session.executeWithRequestId (tsserver.js:90384:28)
    at IOSession.Session.executeCommand (tsserver.js:90393:33)
    at IOSession.Session.onMessage (tsserver.js:90413:35)
    at Interface.<anonymous> (tsserver.js:91614:27)
    at emitOne (events.js:96:13)
    at Interface.emit (events.js:191:7)
    at Interface._onLine (readline.js:241:10)
    at Interface._normalWrite (readline.js:384:12)
    at Socket.ondata (readline.js:101:10)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:191:7)
    at readableAddChunk (_stream_readable.js:178:18)
    at Socket.Readable.push (_stream_readable.js:136:10)
    at Pipe.onread (net.js:560:20)

[mhegazy]

looks related to #20785

[aozgaa]

This issue reproduced in the following context:
TypeScript Version Prefix: 2.7.2
VSCode Version 1.21.0-insider
command requested: occurrences
hitting sessions: 250
proportion of all sessions: 0.0051325217105668355
stack

Error: Could not find file
    at getValidSourceFile (tsserver.js:82897:23)
    at getDocumentHighlights (tsserver.js:83132:30)
    at getOccurrencesAtPositionCore (tsserver.js:83136:46)
    at Object.getOccurrencesAtPosition (tsserver.js:83122:27)
    at IOSession.Session.getOccurrences (tsserver.js:89656:64)
    at Session.handlers.ts.createMapFromTemplate._a.(anonymous function) (tsserver.js:89272:61)
    at unknown (tsserver.js:90553:88)
    at IOSession.Session.executeWithRequestId (tsserver.js:90544:28)
    at IOSession.Session.executeCommand (tsserver.js:90553:33)
    at IOSession.Session.onMessage (tsserver.js:90573:35)
    at Interface.<anonymous> (tsserver.js:91774:27)
    at emitOne (events.js:96:13)
    at Interface.emit (events.js:191:7)
    at Interface._onLine (readline.js:241:10)
    at Interface._normalWrite (readline.js:384:12)
    at Socket.ondata (readline.js:101:10)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:191:7)
    at readableAddChunk (_stream_readable.js:178:18)
    at Socket.Readable.push (_stream_readable.js:136:10)
    at Pipe.onread (net.js:560:20)

[ghost]

Duplicate of #20785