Refactor out getAlignment method

lib/src/utils/string_helper.dart

@@ -1,3 +1,5 @@
+import 'package:flutter/cupertino.dart';
+
 Map<String, String> parseKeyValuePairs(String s, Set<String> targetKeys) {
   final result = <String, String>{};
   final pairs = s.split(';');
@@ -14,3 +16,37 @@ Map<String, String> parseKeyValuePairs(String s, Set<String> targetKeys) {
 
   return result;
 }
+
+Alignment getAlignment(String? s) {
+  const _defaultAlignment = Alignment.center;
+  if (s == null) {
+    return _defaultAlignment;
+  }
+
+  final _index = [
+    'topLeft',
+    'topCenter',
+    'topRight',
+    'centerLeft',
+    'center',
+    'centerRight',
+    'bottomLeft',
+    'bottomCenter',
+    'bottomRight'
+  ].indexOf(s);
+  if (_index < 0) {
+    return _defaultAlignment;
+  }
+
+  return [
+    Alignment.topLeft,
+    Alignment.topCenter,
+    Alignment.topRight,
+    Alignment.centerLeft,
+    Alignment.center,
+    Alignment.centerRight,
+    Alignment.bottomLeft,
+    Alignment.bottomCenter,
+    Alignment.bottomRight
+  ][_index];
+}

lib/src/widgets/editor.dart

@@ -165,33 +165,7 @@ Widget defaultEmbedBuilder(
           final m = _attrs['mobileMargin'] == null
               ? 0.0
               : double.parse(_attrs['mobileMargin']!);
-          var a = Alignment.center;
-          if (_attrs['mobileAlignment'] != null) {
-            final _index = [
-              'topLeft',
-              'topCenter',
-              'topRight',
-              'centerLeft',
-              'center',
-              'centerRight',
-              'bottomLeft',
-              'bottomCenter',
-              'bottomRight'
-            ].indexOf(_attrs['mobileAlignment']!);
-            if (_index >= 0) {
-              a = [
-                Alignment.topLeft,
-                Alignment.topCenter,
-                Alignment.topRight,
-                Alignment.centerLeft,
-                Alignment.center,
-                Alignment.centerRight,
-                Alignment.bottomLeft,
-                Alignment.bottomCenter,
-                Alignment.bottomRight
-              ][_index];
-            }
-          }
+          final a = getAlignment(_attrs['mobileAlignment']);
           return Padding(
               padding: EdgeInsets.all(m),
               child: imageUrl.startsWith('http')