title: Collection.Find(....), Collection.FindAll() All throwing exception with message "value can not be null parameter name method"
body: <p><strong>Person Model:</strong></p>
  
  <pre><code>public class Person {
      public Int32  Id   { get; set; }
      public String Name { get; set; }
  }
  </code></pre>
  
  <p><strong>Find Person from DB:</strong></p>
  
  <pre><code>public List&lt;Person&gt; find()
  {
      using (var db = new LiteDatabase(DatabasePathProvider.CacheLiteDbPath))
      {
          var col = db.GetCollection&lt;Person&gt;("Person");
          var list = col.FindOne(m =&gt; m.Name != null);
  
          return list;
      }
  }
  </code></pre>
  
  <p>On executing the find query on the database as shown in the code,
  This exception is thrown with stack trace:</p>
  
  <pre><code>  at System.Dynamic.Utils.ContractUtils.RequiresNotNull (System.Object value, System.String paramName) [0x00003] in &lt;1ea41f79845a40618089713a1d9403c4&gt;:0 
    at System.Linq.Expressions.Expression.Call (System.Reflection.MethodInfo method, System.Linq.Expressions.Expression arg0, System.Linq.Expressions.Expression arg1) [0x00000] in &lt;1ea41f79845a40618089713a1d9403c4&gt;:0 
    at LiteDB.BsonExpression.ParseSingleExpression (LiteDB.StringScanner s, System.Linq.Expressions.ParameterExpression root, System.Linq.Expressions.ParameterExpression current, System.Boolean isRoot) [0x0004c] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at LiteDB.BsonExpression.ParseExpression (LiteDB.StringScanner s, System.Linq.Expressions.ParameterExpression root, System.Linq.Expressions.ParameterExpression current, System.Boolean arithmeticOnly) [0x00000] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at LiteDB.BsonExpression.Compile (LiteDB.StringScanner s, System.Boolean pathOnly, System.Boolean arithmeticOnly) [0x00045] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at LiteDB.BsonExpression.Compile (System.String expression) [0x0003a] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at LiteDB.BsonExpression..ctor (System.String expression) [0x00010] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at LiteDB.Query.Run (LiteDB.CollectionPage col, LiteDB.IndexService indexer) [0x00055] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at LiteDB.LiteEngine+&lt;Find&gt;d__9.MoveNext () [0x000cd] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at LiteDB.LiteEngine+&lt;Find&gt;d__13.MoveNext () [0x001e4] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at LiteDB.LiteCollection`1+&lt;Find&gt;d__17[T].MoveNext () [0x000ba] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at System.Linq.Enumerable.TryGetFirst[TSource] (System.Collections.Generic.IEnumerable`1[T] source, System.Boolean&amp; found) [0x00045] in &lt;1ea41f79845a40618089713a1d9403c4&gt;:0 
    at System.Linq.Enumerable.FirstOrDefault[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x00000] in &lt;1ea41f79845a40618089713a1d9403c4&gt;:0 
    at LiteDB.LiteCollection`1[T].FindOne (System.Linq.Expressions.Expression`1[TDelegate] predicate) [0x0000d] in &lt;a5ae904d7e2141da931e206893177173&gt;:0 
    at UandUST.Cache.Cache+&lt;Find&gt;d__0.MoveNext () [0x000a0] in C:\Users\iMentor\source\repos\ust\UandUSTAppCenterGit\UandUST\UandUST\Cache\Cache.cs:35
  </code></pre>