refactor: guard against null and undefined input values

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---

Author: kgryte

lib/node_modules/@stdlib/ndarray/base/dtype-alignment/lib/main.js

@@ -61,11 +61,14 @@ function dtypeAlignment( dtype ) {
 	if ( TABLE === void 0 ) {
 		TABLE = table();
 	}
-	v = dtype.alignment;
-	if ( isPositiveInteger( v ) ) {
-		return v;
+	if ( dtype ) {
+		v = dtype.alignment;
+		if ( isPositiveInteger( v ) ) {
+			return v;
+		}
+		return TABLE[ resolve( dtype ) ] || null;
 	}
-	return TABLE[ resolve( dtype ) ] || null;
+	return null;
 }
 
 

lib/node_modules/@stdlib/ndarray/base/dtype-alignment/test/test.js

@@ -124,7 +124,17 @@ tape( 'the function returns the alignment for an underlying array data type', fu
 });
 
 tape( 'the function returns `null` if provided an unknown/unsupported data type', function test( t ) {
-	var out = dtypeAlignment( 'foobar' );
-	t.strictEqual( out, null, 'returns expected value' );
+	var values;
+	var out;
+	var i;
+
+	values = [
+		'foobar',
+		null
+	];
+	for ( i = 0; i < values.length; i++ ) {
+		out = dtypeAlignment( values[ i ] );
+		t.strictEqual( out, null, 'returns expected value when provided '+values[ i ] );
+	}
 	t.end();
 });