Decorator parsing after field with ASI'd arrow function fails

[weswigham]

Our RWC is showing some breaking changes that look like a bug in decorator parsing.

⏯ Playground Link

// @strict: true
// @experimentalDecorators: true
// @filename: index.ts
declare var someDecorator: any;
export default class Whatever {
    private _someField = () => {
        return 0;
    }
    @someDecorator
    getThing() {
        return 0;
    }
}

Workbench Repro

We used to parse this fine, but our RWC repo recently picked up that we started throwing a Decorators must precede the name and all keywords of property declarations. on the decorator, which is incorrect. The issue does not occur when the arrow function on the prior line is terminated with a semicolon.

[typescript-bot]

👋 Hi, I'm the Repro bot. I can help narrow down and track compiler bugs across releases! This comment reflects the current state of the repro in this issue running against the nightly TypeScript.

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Issue body code block by @weswigham

❌ Failed: -

• Decorators must precede the name and all keywords of property declarations.

Historical Information

Issue body code block by @weswigham

Version	Reproduction Outputs
Nightly	❌ Failed: - Decorators must precede the name and all keywords of property declarations.
3.9.2, 4.0.2, 4.1.2, 4.2.2, 4.3.2	👍 Compiled