Merge pull request #303 from D-system/standardrb-new-safe-operator

Syntax: use safe operator

lib/csvlint/cli.rb

@@ -104,7 +104,7 @@ def print_error(index, error, dump, color)
         location = "#{error.row ? "Row" : "Column"}: #{location}"
       end
       output_string = "#{index + 1}. "
-      if error.column && @schema && @schema.instance_of?(Csvlint::Schema)
+      if error.column && @schema&.instance_of?(Csvlint::Schema)
         unless @schema.fields[error.column - 1].nil?
           output_string += "#{@schema.fields[error.column - 1].name}: "
         end
@@ -176,7 +176,7 @@ def hashify(error)
         col: error.column
       }
 
-      if error.column && @schema && @schema.instance_of?(Csvlint::Schema) && !@schema.fields[error.column - 1].nil?
+      if error.column && @schema&.instance_of?(Csvlint::Schema) && !@schema.fields[error.column - 1].nil?
         field = @schema.fields[error.column - 1]
         h[:header] = field.name
         h[:constraints] = field.constraints.map { |k, v| [k.underscore, v] }.to_h