refactor: remove unneeded isnan checks

PR-URL: #11693
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: Planeshifter

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/mean/lib/main.js

@@ -21,7 +21,6 @@
 // MODULES //
 
 var isNonNegativeInteger = require( '@stdlib/math/base/assert/is-nonnegative-integer' );
-var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var PINF = require( '@stdlib/constants/float64/pinf' );
 
 
@@ -72,13 +71,6 @@ var PINF = require( '@stdlib/constants/float64/pinf' );
 * // returns NaN
 */
 function mean( N, K, n ) {
-	if (
-		isnan( N ) ||
-		isnan( K ) ||
-		isnan( n )
-	) {
-		return NaN;
-	}
 	if (
 		!isNonNegativeInteger( N ) ||
 		!isNonNegativeInteger( K ) ||