Throws error when encountering HTML comments.

[bartdorsey]

When trying to parse the HTML of a contenteditable area to turn it into markdown, wasavi throws an error in the getStyle function.

caught TypeError: Cannot read properties of undefined (reading 'display')
    at getStyle (agent.js:177:17)
    at ToPlainText.mainloop (agent.js:337:18)
    at ToPlainText.mainloop (agent.js:375:11)
    at ToPlainText.exec (agent.js:429:9)
    at Object.run (agent.js:465:34)
    at getMarkdown (agent.js:1452:19)
    at readContentFromElement (agent.js:1543:22)
    at Agent.prepare (agent.js:789:3)
    at new Agent (agent.js:1259:11)
    at startAgent (agent.js:1287:25)