avoid potentiall null hints in autofill (#2488)

src/Kp2aAutofillParser/AutofillParser.cs

@@ -434,7 +434,7 @@ namespace Kp2aAutofillParser
         public static List<string> ConvertToCanonicalLowerCaseHints(string[] supportedHints)
         {
             List<string> result = new List<string>();
-            foreach (string hint in supportedHints)
+            foreach (string hint in supportedHints.Where(h => h != null))
             {
                 var canonicalHint = ToCanonicalHint(hint);
                 result.Add(canonicalHint.ToLower());
@@ -829,7 +829,7 @@ namespace Kp2aAutofillParser
             // * if there is no such autofill hint, we use IsPassword to 
 
             HashSet<string> autofillHintsOfAllFields = autofillView.InputFields.Where(f => f.AutofillHints != null)
-                .SelectMany(f => f.AutofillHints).Select(AutofillHintsHelper.ToCanonicalHint).ToHashSet();
+                .SelectMany(f => f.AutofillHints).Where(x => x != null).Select(AutofillHintsHelper.ToCanonicalHint).ToHashSet();
             bool hasLoginAutofillHints = autofillHintsOfAllFields.Intersect(_autofillHintsForLogin).Any();
 
             if (hasLoginAutofillHints)
@@ -839,9 +839,9 @@ namespace Kp2aAutofillParser
                     string[] viewHints = viewNode.AutofillHints;
                     if (viewHints == null)
                         continue;
-                    if (viewHints.Select(AutofillHintsHelper.ToCanonicalHint).Intersect(_autofillHintsForLogin).Any())
+                    if (viewHints.Where(h => h != null).Select(AutofillHintsHelper.ToCanonicalHint).Intersect(_autofillHintsForLogin).Any())
                     {
-                        AddFieldToHintMap(viewNode, viewHints.Select(AutofillHintsHelper.ToCanonicalHint).ToHashSet().ToArray());
+                        AddFieldToHintMap(viewNode, viewHints.Where(h => h != null).Select(AutofillHintsHelper.ToCanonicalHint).ToHashSet().ToArray());
                     }
 
                 }

src/keepass2android/Totp/TrayTotpPluginAdapter.cs

@@ -31,8 +31,17 @@ namespace PluginTOTP
 				_muteWarnings = muteWarnings;
 			}
 
+			/// <summary>
+			/// Check if specified Entry contains Settings that are not null.
+			/// </summary>
+			internal bool SettingsCheck(IDictionary<string, string> entryFields)
+			{
+				string settings;
+				entryFields.TryGetValue(SettingsFieldName, out settings);
+				return !String.IsNullOrEmpty(settings);
+			}
 
-			internal bool HasSeed(IDictionary<string, string> entryFields)
+			internal bool SeedCheck(IDictionary<string, string> entryFields)
 			{
 				string seed;
 				entryFields.TryGetValue(SeedFieldName, out seed);
@@ -92,14 +101,14 @@ namespace PluginTOTP
 
 			private string[] SettingsGet(IDictionary<string, string> entryFields)
 			{
-                return entryFields.TryGetValue(SettingsFieldName, out var settings) ? settings.Split(';') : new[] { "30", "6" };
+				return entryFields[SettingsFieldName].Split(';');
 			}
 
 			public TotpData GetTotpData(IDictionary<string, string> entryFields)
 			{
 				TotpData res = new TotpData();
 
-				if (HasSeed(entryFields))
+				if (SettingsCheck(entryFields) && SeedCheck(entryFields))
 				{
 					bool ValidInterval; bool ValidLength; bool ValidUrl;
 					if (SettingsValidate(entryFields, out ValidInterval, out ValidLength, out ValidUrl))