TypeScript Error TS2590: Expression produces a union type that is too complex to represent.

[ehmicky]

Since Execa 9.0.0, when using TypeScript 5.1 or later, the following type error appears:

types/subprocess/stdout.d.ts:18:4 - error TS2590: Expression produces a union type that is too complex to represent.

18  : InputOutputStream<IsInputFd<FdNumber, OptionsType>>;

Or:

types/return/result-stdout.d.ts:33:4 - error TS2590: Expression produces a union type that is too complex to represent.

 33  : ResultStdioItem<
 34  IsObjectFd<ObjectFdNumber, OptionsType>,
... 
 36  OptionsType['encoding']
 37  >;

Apparently the error is not emitted when using tsd, only when using tsc, which is why our type tests did not catch this.

[ehmicky]

PR at #1035.

[ehmicky]

This is still happening but for older TypeScript versions: 5.1, 5.2 and 5.3.

[ehmicky]

Still happening, but this time with TypeScript 4.8 and earlier...