Nullchecks added. Pruned some whitespace.

McRule/ExpressionRule.cs

@@ -50,10 +50,10 @@ namespace McRule {
             Property = input.Item2;
             Value = input.Item3;
         }
-        
+
         /// <summary>
         /// Returns an expression tree targeting an object type based on policy parameters.
-        /// </summary>	
+        /// </summary>
         public Expression<Func<T, bool>>? GetPredicateExpression<T>() {
             if (!(typeof(T).Name.Equals(this.TargetType, StringComparison.CurrentCultureIgnoreCase))) return null;
 
@@ -66,7 +66,7 @@ namespace McRule {
 
         /// <summary>
         /// Returns an expression tree targeting an object type based on policy parameters.
-        /// </summary>	
+        /// </summary>
         public Expression<Func<T, bool>>? GeneratePredicateExpression<T>(ExpressionGenerator generator) {
             if (!(typeof(T).Name.Equals(this.TargetType, StringComparison.CurrentCultureIgnoreCase))) return null;
 

McRule/PredicateExpressionPolicyExtensions.cs

@@ -410,7 +410,7 @@ public abstract class ExpressionGeneratorBase : ExpressionGenerator
         }
 
         // The value may have the right type and should just be returned.
-        if (comparison is Expression<Func<T, bool>> result) {
+        if (comparison is Expression<Func<T, bool>> result && result != default(Expression<Func<T, bool>>)) {
             return result;
         }