ConditionalPick: Address review feedback

- Use `infer Keys` to avoid evaluating `ConditionalKeys` twice
- Use `expectType<never>` instead of `expectNever` to avoid unreachable code warnings

Author: derodero24

source/conditional-pick.d.ts

@@ -39,8 +39,10 @@ type StringKeysOnly = ConditionalPick<Example, string>;
 
 @category Object
 */
-export type ConditionalPick<Base, Condition> = IsNever<ConditionalKeys<Base, Condition>> extends true
-	? never
-	: Pick<Base, ConditionalKeys<Base, Condition>>;
+export type ConditionalPick<Base, Condition> = ConditionalKeys<Base, Condition> extends infer Keys
+	? IsNever<Keys> extends true
+		? never
+		: Pick<Base, Keys & keyof Base>
+	: never;
 
 export {};

test-d/conditional-pick.ts

@@ -1,4 +1,4 @@
-import {expectNever, expectType} from 'tsd';
+import {expectType} from 'tsd';
 import type {ConditionalPick, Primitive} from '../index.d.ts';
 
 class Awesome {
@@ -29,7 +29,7 @@ expectType<{a: string; c?: string}>(exampleConditionalPickWithUndefined);
 
 // Returns `never` when no keys match the condition
 declare const noMatchingKeys: ConditionalPick<Example, number>;
-expectNever(noMatchingKeys);
+expectType<never>(noMatchingKeys);
 
 declare const noMatchingKeysBoolean: ConditionalPick<{a: string; b: number}, boolean>;
-expectNever(noMatchingKeysBoolean);
+expectType<never>(noMatchingKeysBoolean);