test: increase code coverage in blas/base/zaxpy

PR-URL: #6568
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: ShabiShett07

lib/node_modules/@stdlib/blas/base/zaxpy/lib/ndarray.js

@@ -64,10 +64,7 @@ function zaxpy( N, za, zx, strideX, offsetX, zy, strideY, offsetY ) {
 	var im;
 	var i;
 
-	if ( N <= 0 ) {
-		return zy;
-	}
-	if ( dcabs1( za ) === 0.0 ) {
+	if ( N <= 0 || dcabs1( za ) === 0.0 ) {
 		return zy;
 	}
 	re = real( za );