fix: test error

Author: Neerajpathak07

lib/node_modules/@stdlib/stats/base/dists/chisquare/mean/test/test.native.js

@@ -58,10 +58,10 @@ tape( 'if provided a degrees of freedom parameter `k` that is not a nonnegative
 	var v;
 
 	v = mean( -1.0 );
-	t.equal( isnan( v ), false, 'returns NaN' );
+	t.equal( isnan( v ), true, 'returns NaN' );
 
 	v = mean( NINF );
-	t.equal( isnan( v ), false, 'returns NaN' );
+	t.equal( isnan( v ), true, 'returns NaN' );
 
 	t.end();
 });