TypeError: Cannot read property 'kind' of undefined in 'Object.isIdentifier' during 'getApplicableRefactors'

[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 1.19.3
command requested: getApplicableRefactors
hitting sessions: 5469
proportion of all sessions: 0.0204163913496321
five line hash: 3ba58056c0d0fc407907dd09aad9434c
stack

TypeError: Cannot read property 'kind' of undefined
    at Object.isIdentifier (tsserver.js:9638:20)
    at Object.isExportsIdentifier (tsserver.js:7262:19)
    at Object.isExportsOrModuleExportsOrAlias (tsserver.js:19987:19)
    at isAtTriggerLocation (tsserver.js:80032:31)
    at isAtTriggerLocation (tsserver.js:80037:44)
    at Object.getAvailableActions (tsserver.js:80009:21)
    at unknown (tsserver.js:77123:128)
    at getIterator (tsserver.js:1733:23)
    at Object.next (tsserver.js:1728:35)
    at Object.arrayFrom (tsserver.js:2267:32)
    at Object.getApplicableRefactors (tsserver.js:77122:23)
    at Object.getApplicableRefactors (tsserver.js:83337:32)
    at IOSession.Session.getApplicableRefactors (tsserver.js:90194:53)
    at Session.handlers.ts.createMapFromTemplate._a.(anonymous function) (tsserver.js:89150:61)
    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)

[amcasey]

This is in the "Convert to ES6 module" code fix.

[amcasey]

VariableDeclaration.initializer is optional and isExportsOrModuleExportsOrAlias doesn't handle undefined.

[aozgaa]

This issue reproduced in the following context:
TypeScript Version Prefix: 2.7.2
VSCode Version 1.20.1
command requested: getApplicableRefactors
hitting sessions: 996
proportion of all sessions: 0.020447966494898273
stack

TypeError: Cannot read property 'kind' of undefined
    at Object.isIdentifier (tsserver.js:9640:20)
    at Object.isExportsIdentifier (tsserver.js:7264:19)
    at Object.isExportsOrModuleExportsOrAlias (tsserver.js:19989:19)
    at isAtTriggerLocation (tsserver.js:80192:31)
    at isAtTriggerLocation (tsserver.js:80197:44)
    at Object.getAvailableActions (tsserver.js:80169:21)
    at unknown (tsserver.js:77283:128)
    at getIterator (tsserver.js:1734:23)
    at Object.next (tsserver.js:1729:35)
    at Object.arrayFrom (tsserver.js:2268:32)
    at Object.getApplicableRefactors (tsserver.js:77282:23)
    at Object.getApplicableRefactors (tsserver.js:83497:32)
    at IOSession.Session.getApplicableRefactors (tsserver.js:90354:53)
    at Session.handlers.ts.createMapFromTemplate._a.(anonymous function) (tsserver.js:89310:61)
    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)