Getting property overridden error for dataVersion()

[TheInvoker]

Category

• Bug

Describe the bug

I get this error
https://imgur.com/qv6u8Jh

Steps to reproduce

Load the basic React tutorial template, no more changes needed

Expected behavior

No error

Environment details (development & target environment)

Windows 10
SharePoint Online
Node.js v10
Chrome v79
VS Code | SPFx v1.10.0

[msft-github-bot]

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[stchiew]

Seeing this for me as well after upgrading VS Code to August 2020 (v 1.49)

[stchiew]

I can get rid of this error by changing the Typescript version in VSCode in use for the project workspace(v3.3), instead of using VSCode's default 4.0.2 (introduced in VSCode August 2020 release).
You can change the typescript version at the bottom right of the editor sceeen - click on the version number next to Typescript, then at the top of the editor screen select your workspace's typescript version.

[TheInvoker]

So to fix it we just need to set the ts version to what the spfx ts version is, which is v3.3?

[stchiew]

So to fix it we just need to set the ts version to what the spfx ts version is, which is v3.3?

Yes.
The bigger question will be:
Is this an SPFX issue, Typescript 4 issue or VSCode intellisense issue.

[TheInvoker]

Good thing all of those are Microsoft owned lol

[andrewconnell]

This isn't really a SPFx issue... just two versions of TypeScript conflict. The solution above by @stchiew would be the best approach.

[deanbot]

Using TS 4.X in VSCode provides a better authoring experience...

I'm opting to ignore the IDE errors re 'overridden as an accessor' since they are not compile errors.

That said, moving these accessor overrides into the constructor like so may be a workaround if the warnings really bother you (not tested):

constructor() {
    super();
    Object.defineProperty(this, "dataVersion", {
      get() {
        return Version.parse('1.0');
      }
    });
  }
  
  // protected get dataVersion(): Version {
  //   return Version.parse('1.0');
  // }

• via Add useDefineForClassFields flag for Set -> Define property declaration microsoft/TypeScript#33509 (comment)

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