Language service frequently stops in these days

[falsandtru]

Language service warns wrong errors based on old code and I have to restart language service.

TypeScript Version: 3.4.0-dev.20190817

VSCode 1.37.1

[2019-08-18 01:55:51.644] [exthost] [error] Error: <semantic> TypeScript Server Error (3.7.0-dev.20190817)
Not supported
Error: Not supported
    at Object.get yieldType [as yieldType] (tsserver.js:32546:37)
    at getIteratedTypeOrElementType (tsserver.js:57722:61)
    at getContextualTypeForElementExpression (tsserver.js:49558:20)
    at checkArrayLiteral (tsserver.js:50019:49)
    at checkExpressionWorker (tsserver.js:55222:28)
    at checkExpression (tsserver.js:55147:38)
    at checkFunctionExpressionOrObjectLiteralMethodDeferred (tsserver.js:53886:36)
    at checkDeferredNode (tsserver.js:59994:21)
    at Map.forEach (<anonymous>)
    at checkDeferredNodes (tsserver.js:59982:37)
    at checkSourceFileWorker (tsserver.js:60044:17)
    at checkSourceFile (tsserver.js:60014:13)
    at getDiagnosticsWorker (tsserver.js:60089:17)
    at Object.getDiagnostics (tsserver.js:60075:24)
    at isMissingAwaitError (tsserver.js:116089:39)
    at getAwaitableExpression (tsserver.js:116110:20)
    at Object.getCodeActions (tsserver.js:116050:34)
    at tsserver.js:115926:121
    at Object.flatMap (tsserver.js:583:25)
    at Object.getFixes (tsserver.js:115926:23)
    at tsserver.js:125977:35
    at Object.flatMap (tsserver.js:583:25)
    at Object.getCodeFixesAtPosition (tsserver.js:125975:23)
    at IOSession.Session.getCodeFixes (tsserver.js:135174:64)
    at Session.handlers.ts.createMapFromTemplate._a.(anonymous function) (tsserver.js:133961:61)
    at tsserver.js:135367:88
    at IOSession.Session.executeWithRequestId (tsserver.js:135358:28)
    at IOSession.Session.executeCommand (tsserver.js:135367:33)
    at IOSession.Session.onMessage (tsserver.js:135390:35)
    at Interface.<anonymous> (tsserver.js:136705:27)
    at Interface.emit (events.js:182:13)
    at Interface._onLine (readline.js:290:10)
    at Interface._normalWrite (readline.js:433:12)
    at Socket.ondata (readline.js:149:10)
    at Socket.emit (events.js:182:13)
    at addChunk (_stream_readable.js:283:12)
    at readableAddChunk (_stream_readable.js:264:11)
    at Socket.Readable.push (_stream_readable.js:219:10)
    at Pipe.onStreamRead [as onread] (internal/stream_base_commons.js:94:17)
	at Function.create (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\extensions\typescript-language-features\dist\extension.js:53:63463)
	at h.dispatchResponse (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\extensions\typescript-language-features\dist\extension.js:53:56618)
	at h.dispatchMessage (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\extensions\typescript-language-features\dist\extension.js:53:55516)
	at constructor._reader.onData.e (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\extensions\typescript-language-features\dist\extension.js:53:54992)
	at u.fire (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\services\extensions\node\extensionHostProcess.js:50:207)
	at t.Reader.onLengthData (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\extensions\typescript-language-features\dist\extension.js:53:61683)
	at Socket.t.Reader.constructor.e.on.e (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\extensions\typescript-language-features\dist\extension.js:53:61331)
	at Socket.emit (events.js:182:13)
	at addChunk (_stream_readable.js:283:12)
	at readableAddChunk (_stream_readable.js:264:11)
	at Socket.Readable.push (_stream_readable.js:219:10)
	at Pipe.onStreamRead [as onread] (internal/stream_base_commons.js:94:17)

[2019-08-17 16:27:42.203] [exthost] [error] Error: DisposableStore is missing...
	at R._convertCompletionItem (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\services\extensions\node\extensionHostProcess.js:563:173)
	at define.resolveCompletionItem.o.asPromise.then.e (c:\Users\\AppData\Local\Programs\Microsoft VS Code\resources\app\out\vs\workbench\services\extensions\node\extensionHostProcess.js:562:707)

[falsandtru]

This error may be caused by #32955.

[falsandtru]

Confirmed this problem appeared without any errors. All output panels are useless.

[falsandtru]

The errors might be hidden by the update of TS.

[rbuckton]

@falsandtru do you have a minimal repro to trigger this in the editor? I haven't been able to craft a test case that triggers this.

[falsandtru]

The problem which stops/breaks language service locally appears when I mistype something and fix it like mistyping refs and fixing it to return. Then language service warns based on the removed word refs. But unfortunately this is not reproducible because this is time-sensitive. Have you seen a similar problem?

[RyanCavanaugh]

@falsandtru we had a couple sets of eyes try to figure out how this happens, but weren't able to come up with any way to trigger this. The way the code is written seems to make this impossible, but obviously it's happening anyway. Can you provide a concrete repro where we can try to cause the crash locally and understand what the problem is? Thanks!

[falsandtru]

I found a repro! This is reproducible on both Ubuntu 18.04 and Win10.

1. clone https://github.com/falsandtru/securemark
2. run npm i
3. run code --disable-extensions
4. open ./src/util/figure.ts
5. insert 72th line (refer the ss)
6. type ret
7. wait for return to appear in the suggestions and type ttt... immediately! this is very important.
8. delete the verbose t
9. language service suggests return again
10. complete return by choosing the suggested return
11. the error based on the removed code remains and we can't remove this.