optimize logic, cleanup code

Author: tinohager

src/Nager.PublicSuffix/DomainParser.cs

@@ -102,12 +102,6 @@ public bool IsValidDomain(string fullyQualifiedDomainName)
                     return false;
                 }
 
-                var domainDataStructure = this._ruleProvider.GetDomainDataStructure();
-                if (domainDataStructure == null || domainDataStructure.TldRule == null)
-                {
-                    return false;
-                }
-
                 if (string.IsNullOrEmpty(domainInfo.Domain))
                 {
                     return false;
@@ -136,7 +130,7 @@ public bool IsValidDomain(string fullyQualifiedDomainName)
             }
 
             var domainDataStructure = this._ruleProvider.GetDomainDataStructure();
-            if (domainDataStructure == null)
+            if (domainDataStructure == null || domainDataStructure.TldRule == null)
             {
                 throw new NullReferenceException("DomainDataStructure is not available");
             }

src/Nager.PublicSuffix/RuleParsers/TldRuleParser.cs

@@ -9,7 +9,7 @@ namespace Nager.PublicSuffix.RuleParsers
     /// </summary>
     public class TldRuleParser
     {
-        private readonly char[] _lineBreak = new char[] { '\n', '\r' };
+        private readonly char[] _lineBreak = ['\n', '\r'];
 
         /// <summary>
         /// ParseRules

src/Nager.PublicSuffix/RuleProviders/StaticRuleProvider.cs

@@ -16,7 +16,7 @@ public class StaticRuleProvider : BaseRuleProvider
         /// <param name="domainDataStructure"></param>
         public StaticRuleProvider(DomainDataStructure domainDataStructure)
         {
-            this._domainDataStructure = domainDataStructure;
+            base._domainDataStructure = domainDataStructure;
         }
 
         /// <summary>