Debug Failure. False expression. in `collectEnclosingScopes` during `getApplicableRefactors `

[aozgaa]

tsserver version: 2.6.1
hits: at least 773561
stack:

Error: Debug Failure. False expression.
    at Object.first (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:1898:15)
    at collectEnclosingScopes (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:77840:65)
    at getPossibleExtractionsWorker (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:77922:30)
    at getPossibleExtractions (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:77881:26)
    at Object.getAvailableActions (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:77514:35)
    at c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:75017:128
    at Object.flatMapIter (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:1570:23)
    at Object.getApplicableRefactors (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:75016:23)
    at Object.getApplicableRefactors (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:80232:32)
    at IOSession.Session.getApplicableRefactors (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:86474:53)
    at Session.handlers.ts.createMapFromTemplate._a.(anonymous function) (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:85436:61)
    at c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:86669:88
    at IOSession.Session.executeWithRequestId (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:86660:28)
    at IOSession.Session.executeCommand (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:86669:33)
    at IOSession.Session.onMessage (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:86689:35)
    at Interface.<anonymous> (c:\Program Files\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:87881:27)
    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]

The Source: Telemetry have limited information. we only have the call stack from the crash report. We need to either mitigate the crash, or add additional asserts to get more information in future crash reports.

[amcasey]

This appears to indicate that range.range is an empty array (but not undefined?) in collectEnclosingScopes.

[amcasey]

The loop assumes that all children of a BlockLike are in Statements. That is not the case for, e.g., the expression of a CaseClause. Curiously though, that case seems to tripping a different assert.

[amcasey]

Repro:

switch (x) {
    case /*start*/1:
        break;/*end*/
}