In case of an error (file not found) it throws an error and send a payload with msg.error.
According to node help that should not be the case. In addition I cant find the "node configuration"
Node help says:
Legacy error handling
Before Node-RED 0.17, if this node hit an error whilst reading the file, it would send a message with no
msg.errorset to the details of the error. This is a deprecated mode of behaviour for the node that new instances will not do. If required, this mode can be re-enabled within the node configuration.
Errors should be caught and handled using a Catch node.