Error 501 Method ET is not defined in RFC 2068 and is not supported by the Servlet API

[gwynethsc]

Encountered intermittently when sending GET requests to /data and /login servlets during comment deletion

[gwynethsc]

First encountered at commit 986dc5f "Add functionality to permanently delete individual comments"

[gwynethsc]

Not yet encountered on the deployed live site

[gwynethsc]

Does not occur when comment fetching is divorced from deletion --- i.e., removed from .then() statement and given its own button. However, simply delaying the fetch call with setTimeout() for up to 3 seconds did NOT eliminate the error

[gwynethsc]

Hypothesized to have the same root cause as error "405 - JSPs only permit GET POST or HEAD"

currently working around by not using JSP

[gwynethsc]

Suggestion from wdtseng@
Implement a retry with backoff, since the error is intermittent