Debug Failure. False expression. in `findPrecedingToken` during `getQuickInfoAtPosition`

[aozgaa]

tsserver version: 2.6.1
hits: at least 570381
stack:

Error: Debug Failure. False expression.
    at findPrecedingToken (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:62860:18)
    at getTokenAtPositionWorker (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:62822:41)
    at getTouchingToken (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:62794:16)
    at Object.getTouchingPropertyName (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:62790:16)
    at Object.getQuickInfoAtPosition (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:79791:27)
    at IOSession.Session.getQuickInfoWorker (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:86102:62)
    at Session.handlers.ts.createMapFromTemplate._a.(anonymous function) (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:85266:61)
    at /Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:86669:88
    at IOSession.Session.executeWithRequestId (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:86660:28)
    at IOSession.Session.executeCommand (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:86669:33)
    at IOSession.Session.onMessage (/Applications/Visual Studio Code.app/Contents/Resources/app/extensions/node_modules/typescript/lib/tsserver.js:86689:35)
    at Interface.<anonymous> (/Applications/Visual Studio Code.app/Contents/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)

@aozgaa It looks like that assertion was added in #16385.

[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.

[aozgaa]

repro's in 2.7.0 with the following statistics:

TypeScript Version:
2.7.0
VSCode Version
1.20.0-insider
command requested
quickinfo
hitting sessions
1812
proportion of all sessions
0.0319047786738036

[mhegazy]

Closing in favor of #21799