Incorrect Partial Type + Discriminated Union Exhaustion Typecheck

**Describe the bug** In the below example, the exhaustive check is failing but all cases appear to be covered and versions up to 5.6 work as expected **TypeScript playground with a minimal reproduction case** ```typescript type Inner = | { discriminator: 'a'; context: string; } | { discriminator: 'b'; context: boolean; } | { discriminator: 'c'; context: Date; }; type T = { id: string; } & Partial<Inner>; const parse = (x: T | undefined) => { return match(x) .with(undefined, () => null) .with({ discriminator: P.nullish }, () => null) .with( { discriminator: 'a', context: P.select() }, (accountName) => accountName ) .with( { discriminator: 'b', context: P.select() }, (openedDate) => openedDate ) .with( { discriminator: 'c', context: P.select() }, (isKnown) => isKnown ) .exhaustive(); // claims that there is an unhandled case }; ``` **Versions** - TypeScript version: 5.9.3 - ts-pattern version: 5.9.0 (last working minor version is 5.6) - environment: VSCode, Chrome, CodeSandbox