TS 5.8 TypeError: Cannot read properties of undefined (reading 'kind')

🔎 Search Terms

TypeError: Cannot read properties of undefined (reading 'kind')

🕗 Version & Regression Information

This changed between versions 5.7.3 and 5.8.2
This changed in commit or PR Computed names in declarations files are resolved even when non-literal, preserve computed names when expressions are entity names #60052

⏯ Playground Link

https://www.typescriptlang.org/dev/bug-workbench/?ts=5.8.2#code/KYDwDg9gTgLgBDAnmYcDKMCGNUF44DeAsAFBxyYBccAdgK4C2ARsFANynlPUDOMUASxoBzDiQC+Y0qEiw4AYwA2mHjzgAVYH2Jk4PYDAzZgACj7HqRnAEoC4zgi3x8J4NUw1E1uLgB8hB3IAM2g4E3kIGj44AG0Aa2BEABo4ADdMRTpgAF04CCC4AHkmACtgeRgAOmAafgEtV2tvHXJWhAALAR5K-UMsHBMWttb4xOzqdMzgJMDW8WsxNvtdSVJl0iA

💻 Code

export type State = {
  a: number;
  b: string;
};

export class Test{
  setState(state: State){}
  test = (e: any) => {
    for (const [key, value] of Object.entries(e)) {
      this.setState({
        [key]: value,
      });
    }
  };
}

🙁 Actual behavior

running tsc results in a crash:

TypeError: Cannot read properties of undefined (reading 'kind')

🙂 Expected behavior

No crash is expected, some type errors should be found instead.

Additional information about the issue

No response

I'm also hitting this. Here's the MRE: https://www.typescriptlang.org/play/?#code/C4TwDgpgBAwg9gO2AQwJYIgJwDwGkIgDOUEAHsBAgCbGHCboDmAfFALxQDeAUFFANr4QUdFCGEAugC4oAIzhwANhGQIA3NwC+3bgGNEdKPoR1VwGfCRoMOAEQAzBbagAfKLdnJMt1hx59HOBl6AFcIABpeOS8Ze2RFQgitHXsQhF1gVEQoKhAEZABbVF08AmIyCmpaeiZmAAp7VEw6GXFw6MYZAFlkMFKidvklFQRmAEoLRBR0LH7CVn8oZWAoTAhCEMVzWCnrWfFWNzSqCEaMKnYoY9OZqg0ox0woOuNDfgBrAnaAN3iwiSgcHsHQAdJQaus6mMxlwonxUMC6gBCNYbLYw1GbFZ+ASfEDSKC-RRhKCaDR8PgQBLQTFbD4EAEcIlhcmknR8NbAEKYBCrdZYjTabi5fJFXR1BxOdoYADuUB6YDq-H4krgtnaoQgEnaKs83nacWpEgk0KAA

Wondering what the status of this one is and if the linked PR can be reviewed / merged?

It seems the compiler fails to use variables declared by a tuple as index keys. For those of you looking for a workaround in the meantime: redefine your tuples to rather be normal variables (using Object.keys and Object.values for above example) instead.

Workaround

Before

for (const [key, value] of Object.entries(data)) {
    data = { [key]: value };
}

After

for (const key in data) {
    data = { [key]: data[key] };
}

An alternative, potentially a bit more type-friendly workaround (e.g. when using noUncheckedIndexedAccess ) is to keep using Object.entries() but destructure the entries in a separate statement.

Before

for (const [key, value] of Object.entries(data)) {
    console.log(key, value);
}

After

for (const entry of Object.entries(data)) {
    const [key, value] = entry;
    console.log(key, value);
}

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TS 5.8 TypeError: Cannot read properties of undefined (reading 'kind') #61351

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TS 5.8 TypeError: Cannot read properties of undefined (reading 'kind') #61351

Description

🔎 Search Terms

🕗 Version & Regression Information

⏯ Playground Link

💻 Code

🙁 Actual behavior

🙂 Expected behavior

Additional information about the issue

Activity

will-path commented on Apr 7, 2025

lnunno commented on May 28, 2025

RudiVuuren commented on Jun 4, 2025

Workaround

Before

After

martinslota commented on Jun 17, 2025

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