There are a couple steps here:

• replace the free-form string in the Result that network listeners receive with the LoadError type from http_loader.rs
• propagate the errors from load_for_consumer to the network receiver instead of sending a string
• convert the other network loaders to use the LoadError values
• move the SSL validation error handling into the HTML parser network listener (servohtmlparser.rs)
• make headers_available take a Result<Metadata, LoadError> value to reflect the possibility of early errors (such as SSL validation failure)