fixed newznab validation when URL is null.

src/NzbDrone.Core.Test/IndexerTests/NewznabTests/NewznabSettingFixture.cs

@@ -24,6 +24,24 @@ namespace NzbDrone.Core.Test.IndexerTests.NewznabTests
 
         }
 
+        [TestCase("")]
+        [TestCase("  ")]
+        [TestCase(null)]
+        public void invalid_url_should_not_apikey(string url)
+        {
+            var setting = new NewznabSettings
+            {
+                ApiKey = "",
+                Url = url
+            };
+
+
+            setting.Validate().IsValid.Should().BeFalse();
+            setting.Validate().Errors.Should().NotContain(c => c.PropertyName == "ApiKey");
+            setting.Validate().Errors.Should().Contain(c => c.PropertyName == "Url");
+
+        }
+
 
         [TestCase("http://nzbs2.org")]
         public void doesnt_requires_apikey(string url)

src/NzbDrone.Core/Indexers/Newznab/NewznabSettings.cs

@@ -23,6 +23,11 @@ namespace NzbDrone.Core.Indexers.Newznab
 
         private static bool ShouldHaveApiKey(NewznabSettings settings)
         {
+            if (settings.Url == null)
+            {
+                return false;
+            }
+
             return ApiKeyWhiteList.Any(c => settings.Url.ToLowerInvariant().Contains(c));
         }