Build fails with typescript 3.8.2

[mydea]

Please paste the output of ember -v here

ember-cli: 3.16.0
node: 12.13.1
os: linux x64

Please paste the output of tsc -v here

Version 3.8.2

Please paste the version of ember-cli-typescript and ember-cli-typescript-blueprints here

├─ @glimmer/component@1.0.0
│ └─ ember-cli-typescript@3.0.0
├─ ember-cli-typescript-blueprints@3.0.0
├─ ember-cli-typescript@3.1.3
├─ ember-concurrency-decorators@1.0.0
│ └─ ember-cli-typescript@2.0.2
└─ ember-load-initializers@2.1.1
└─ ember-cli-typescript@2.0.2

What are instructions we can follow to reproduce the issue?

yarn upgrade typescript@3.8.2
ember build

Reproduction Case

Updating typescript from 3.7.5 to 3.8.2 breaks the build. Downgrading again fixes it.

Now about that bug. What did you expect to see?

I can build the app.

What happened instead?

[Bundler]/my-ember-addon/node_modules/typescript/lib/typescript.js:98632
                throw e;
                ^

Error: Debug Failure.
    at Object.assertDefined (/my-ember-addon/node_modules/typescript/lib/typescript.js:2227:24)
    at /my-ember-addon/node_modules/typescript/lib/typescript.js:39435:34
    at Object.filter (/my-ember-addon/node_modules/typescript/lib/typescript.js:513:31)
    at serializeAsClass (/my-ember-addon/node_modules/typescript/lib/typescript.js:39433:48)
    at serializeSymbolWorker (/my-ember-addon/node_modules/typescript/lib/typescript.js:39164:29)
    at serializeSymbol (/my-ember-addon/node_modules/typescript/lib/typescript.js:39105:38)
    at /my-ember-addon/node_modules/typescript/lib/typescript.js:39080:25
    at Map.forEach (<anonymous>)
    at visitSymbolTable (/my-ember-addon/node_modules/typescript/lib/typescript.js:39079:33)
    at symbolTableToDeclarationStatements (/my-ember-addon/node_modules/typescript/lib/typescript.js:38950:17)
⠹ building... [Bundler](node:25503) UnhandledPromiseRejectionWarning: Error: Debug Failure.
    at CommandCoordinator.dispatchResponse (/my-ember-addon/node_modules/stagehand/lib/command-coordinator.js:54:69)
    at CommandCoordinator.<anonymous> (/my-ember-addon/node_modules/stagehand/lib/command-coordinator.js:43:29)
    at Generator.next (<anonymous>)
    at /my-ember-addon/node_modules/stagehand/lib/command-coordinator.js:7:71
    at new Promise (<anonymous>)
    at __awaiter (/my-ember-addon/node_modules/stagehand/lib/command-coordinator.js:3:12)
    at CommandCoordinator.messageReceived (/my-ember-addon/node_modules/stagehand/lib/command-coordinator.js:40:16)
    at ChildProcess.emit (events.js:210:5)
    at emit (internal/child_process.js:876:12)
    at processTicksAndRejections (internal/process/task_queues.js:81:21)
(node:25503) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:25503) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

I think this is the actual issue at the core of #1101

[FrankWang117]

change typescript version from ^3.8.2 to 3.7.5.
in terminal:

yarn add typescript@3.7.5

[mydea]

Yes, downgrading to 3.7.5 works!

[chriskrycho]

We're watching TS 3.8 releases closely, and not currently recommending it to anyone because of the amount of breakage we're seeing. In case anyone else comes along: I'll update this comment and add another one if/when we see a solid-enough 3.8 point release or if 3.9 stabilizes these issues.

[dfreeman]

I've got this narrowed down to a relatively small reproduction in https://github.com/dfreeman/typescript-3.8-debug-failure, and bisected the 3.8-dev releases to find which one it started happening in.

I reported what I found on microsoft/TypeScript#37015 (comment), which will hopefully be reopened (and likely shouldn't have been closed in the first place), so we'll see what happens from here.

[jamescdavis]

Update: the issue has since been reopened, labeled a bug, and added to the TS 3.9 milestone.

[luketheobscure]

Might want to change what's installed by default. I got this on a brand new project after just ember new foo and ember install ember-cli-typescript.

[chriskrycho]

@luketheobscure it's a reasonable thought, but there's a tradeoff there: it means constant vetting of new TS versions and bumps here, and cutting a looooot more releases. That's not a massive amount of work, but it's also not nothing. I think it's likely we will get there, but none of us have the time to do that at the moment. 😬

That said, the reason I think it's likely we'll get there is that we have a medium-term goal of improving stability and reliability throughout the Ember TS ecosystem (hopefully with benefits for the wider TS ecosystem as well!) and adjusting this is likely a part of that.

[igbopie]

so sad! I was going to use a dep that is using a ts 3.8 feature... but I can't :(

[mydea]

So with TS 3.9.2, our build is passing again 🎉 . Do you think it is safe to update to 3.9.2 (and close this issue)?

[chriskrycho]

Yep! Was actually going to circle back this week and check! If anyone else has this issue in 3.9 please report here and we'll reopen.

[igbopie]

Yay! I have different issues now, related to mirage, but this one is gone!