Cleanup after merge: Move declaration closer to usage (#712)

Author: Bart Koelman

src/JsonApiDotNetCore/Extensions/IQueryableExtensions.cs

@@ -245,8 +245,7 @@ private static IQueryable<TSource> CallGenericWhereMethod<TSource>(IQueryable<TS
             var concreteType = typeof(TSource);
             PropertyInfo property;
             MemberExpression left;
-            Expression right;
-            
+
             // {model}
             var parameter = Expression.Parameter(concreteType, "model");
             // Is relationship attribute
@@ -278,6 +277,7 @@ private static IQueryable<TSource> CallGenericWhereMethod<TSource>(IQueryable<TS
 
             try
             {
+                Expression right;
                 if (op == FilterOperation.isnotnull || op == FilterOperation.isnull)
                     right = Expression.Constant(null);
                 else