Add null safety for the "where" clause extraction

Author: theSlyest

Parse/Platform/LiveQueries/ParseLiveQuery.cs

@@ -38,6 +38,8 @@ public class ParseLiveQuery<T> where T : ParseObject
 
     public ParseLiveQuery(IServiceHub serviceHub, string className, IDictionary<string, object> filters, IEnumerable<string> selectedKeys = null, IEnumerable<string> watchedKeys = null)
     {
+        ArgumentNullException.ThrowIfNull(filters);
+
         Services = serviceHub;
         ClassName = className;
         Filters = filters;

Parse/Platform/Queries/ParseQuery.cs

@@ -912,9 +912,15 @@ public override int GetHashCode()
         return 0;
     }
 
+    /// <summary>
+    /// Converts the current query into a live query that allows real-time updates to be monitored
+    /// for changes that match the specified query criteria.
+    /// </summary>
+    /// <returns>A ParseLiveQuery object configured to monitor changes for the query.</returns>
     public ParseLiveQuery<T> GetLive()
     {
-        IDictionary<string, object> paramsDict = BuildParameters();
-        return new ParseLiveQuery<T>(Services, ClassName, paramsDict["where"] as IDictionary<string, object>, KeySelections);
+        ArgumentNullException.ThrowIfNull(Filters);
+        IDictionary<string, object> filters = BuildParameters().TryGetValue("where", out object where) ? where as IDictionary<string, object> : null;
+        return new ParseLiveQuery<T>(Services, ClassName, filters, KeySelections);
     }
 }