Throw the correct error when second argument to ow is undefined (#…

…239)

Co-authored-by: Sindre Sorhus <[email protected]>

source/predicates/base-predicate.ts

@@ -8,7 +8,7 @@ export const testSymbol: unique symbol = Symbol('test');
 /**
 @hidden
 */
-export const isPredicate = (value: unknown): value is BasePredicate => Boolean((value as any)[testSymbol]);
+export const isPredicate = (value: unknown): value is BasePredicate => Boolean((value as any)?.[testSymbol]);
 
 /**
 @hidden

test/test.ts

@@ -517,6 +517,10 @@ test('ow without valid arguments', t => {
 	t.throws(() => {
 		ow(5, {} as any);
 	}, {message: 'Expected second argument to be a predicate or a string, got `object`'});
+
+	t.throws(() => {
+		ow(5, undefined);
+	}, {message: 'Expected second argument to be a predicate or a string, got `undefined`'});
 });
 
 // Skipped because require is not defined in esm