fix NullReferenceException if requirement affected by previous requirement has no comparison

Source/ViewModels/RequirementComparisonViewModel.cs

@@ -71,7 +71,13 @@ internal override void OnShowHexValuesChanged(ModelPropertyChangedEventArgs e)
 
         private void UpdateOtherDefinition(NumberFormat numberFormat)
         {
-            OtherDefinition = BuildDefinition(CompareRequirement, numberFormat);
+            OtherDefinition = CompareRequirement != null ? BuildDefinition(CompareRequirement, numberFormat) : "";
+        }
+
+        protected override void UpdateDefinition(NumberFormat numberFormat)
+        {
+            base.UpdateDefinition(numberFormat);
+            UpdateOtherDefinition(numberFormat);
         }
     }
 }

Source/ViewModels/RequirementGroupViewModel.cs

@@ -183,10 +183,7 @@ private static void UpdateDependencies(List<RequirementViewModel> list)
                 requirement.IsValueDependentOnPreviousRequirement = isValueDependentOnPreviousRequirement;
 
                 if (requirement.Requirement == null)
-                {
-                    isValueDependentOnPreviousRequirement = false;
                     continue;
-                }
 
                 switch (requirement.Requirement.Type)
                 {
@@ -203,7 +200,7 @@ private static void UpdateDependencies(List<RequirementViewModel> list)
             }
         }
 
-        private void AppendRequirements(List<RequirementViewModel> list, RequirementEx left, RequirementEx right, NumberFormat numberFormat, IDictionary<uint, CodeNote> notes)
+        private static void AppendRequirements(List<RequirementViewModel> list, RequirementEx left, RequirementEx right, NumberFormat numberFormat, IDictionary<uint, CodeNote> notes)
         {
             if (right == null)
             {

Source/ViewModels/RequirementViewModel.cs

@@ -128,9 +128,9 @@ internal virtual void OnShowHexValuesChanged(ModelPropertyChangedEventArgs e)
                 UpdateDefinition((bool)e.NewValue ? NumberFormat.Hexadecimal : NumberFormat.Decimal);
         }
 
-        private void UpdateDefinition(NumberFormat numberFormat)
+        protected virtual void UpdateDefinition(NumberFormat numberFormat)
         {
-            Definition = BuildDefinition(Requirement, numberFormat);
+            Definition = Requirement != null ? BuildDefinition(Requirement, numberFormat) : "";
         }
 
         protected string BuildDefinition(Requirement requirement, NumberFormat numberFormat)

Tests/ViewModels/RequirementGroupViewModelTests.cs

@@ -38,8 +38,17 @@ class RequirementGroupViewModelTests
             "unless(byte(0x001234) == 7)|OrNext byte(0x001234) == 7\nunless(byte(0x001235) == 6)|unless(byte(0x001235) == 6)")]
         [TestCase("0xH1234=7_0xH1235=6", "N:0xH1234=7_0xH1235=6", // AndNext a,b => a,b
             "byte(0x001234) == 7|AndNext byte(0x001234) == 7\nbyte(0x001235) == 6|byte(0x001235) == 6")]
+        [TestCase("A:0xH1234*100_A:100*1_M:1=333", "A:0xH1234*100_M:101=333", // A*100+100+1=333 => A*100+101=333
+            "byte(0x001234) * 100 + |byte(0x001234) * 100 + \n100 * 1 + |\nmeasured(1 == 333)|measured(101 == 333)")]
+        [TestCase("A:0xH1234*100_M:101=333", "A:0xH1234*100_A:100*1_M:1=333", // A*100+101=333 => A*100+100+1=333
+            "byte(0x001234) * 100 + |byte(0x001234) * 100 + \n|100 * 1 + \nmeasured(101 == 333)|measured(1 == 333)")]
         public void TestDiff(string leftSerialized, string rightSerialized, string expected)
         {
+            var mockSettings = new Mock<ISettings>();
+            mockSettings.Setup(s => s.HexValues).Returns(false);
+            ServiceRepository.Reset();
+            ServiceRepository.Instance.RegisterInstance(mockSettings.Object);
+
             var notes = new Dictionary<uint, CodeNote>();
 
             var builder = new AchievementBuilder();