fix(browser): Accept precisely-typed GrowthBook class in growthbookIntegration

[codr]

Summary

growthbookIntegration({ growthbookClass: GrowthBook }) — the exact call shown in the integration's own docs/JSDoc — does not type-check against the real @growthbook/growthbook GrowthBook class, forcing consumers to cast.

The parameter was typed as a constructor with unknown[] args:

export type GrowthBookClass = new (...args: unknown[]) => GrowthBook;        // @sentry/browser
export type GrowthBookClassLike = new (...args: unknown[]) => GrowthBookLike; // @sentry/core

GrowthBook's real constructor is constructor(options?: Options). A constructor with a narrow parameter is not assignable to one declared with (...args: unknown[]) (constructor parameters are contravariant: unknown is not assignable to Options), so typeof GrowthBook is rejected.

@sentry/core masks this by annotating the export as IntegrationFn ((...rest: any[])), but @sentry/browser re-declares the wrapper with the strict { growthbookClass: GrowthBookClass } parameter via satisfies IntegrationFn, which preserves the strict type — so the public browser/react API requires a cast.

Fix

The integration only ever reads growthbookClass.prototype to monkey-patch isOn / getFeatureValue; it never constructs the class. Typing the parameter as exactly that:

export type GrowthBookClass = { prototype: GrowthBook };
export type GrowthBookClassLike = { prototype: GrowthBookLike };

accepts any class whose instances expose the wrapped surface (so typeof GrowthBook works with no cast), still rejects classes missing isOn / getFeatureValue, and avoids any. It also makes the internal growthbookClass.prototype as GrowthBookLike cast redundant, which is removed.

Test

Adds packages/browser/test/integrations/featureFlags/growthbook/integration.test.ts: passes a mock class with a real, narrow constructor to growthbookIntegration with no cast (the type regression guard) and asserts boolean evaluations are captured to the scope's flag context.

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