Treat nil values as empty predicate

elasticgraph-graphql/lib/elastic_graph/graphql/filtering/filter_interpreter.rb

@@ -62,8 +62,6 @@ def process_filter_hash(bool_node, filter_hash, field_path)
             # `nil` filter predicates should be ignored, so we can safely `compact` them out.
             # It also is simpler to handle them once here instead of the different branches
             # below having to be aware of possible `nil` predicates.
-            expression = expression.compact if expression.is_a?(::Hash)
-
             case filter_node_interpreter.identify_node_type(field_or_op, expression)
             when :empty
               # This is an "empty" filter predicate and we can ignore it.
@@ -313,6 +311,9 @@ def process_list_count_expression(bool_node, expression, field_path)
           # While we index an explicit count of 0, the count field will be missing from documents indexed before
           # the list field was defined on the ElasticGraph schema. To properly match those documents, we need to
           # convert this into an OR (using `any_of`) to also match documents that lack the field entirely.
+          expression = expression.compact
+          return if expression.empty?
+
           unless excludes_zero?(expression)
             expression = {schema_names.any_of => [
               expression,