Dumping some obscure thread within the channel returns invalid JSON: invalid character '<' looking for beginning of value

[rusq]

Describe the bug
An error occurs while trying to dump a DM. Dump runs fine until it meets with the obscure thread. Looking at the error, it seems that HTML is returned by the API.

User is using browser auth, so all set of cookies is set.

To Reproduce
Steps to reproduce the behavior:

1. Run slackdump:

./slackdump DXXXXXXX

Expected behavior
Channel is saved to JSON.

Output

failed to dump channel:thread DXXXXXXX:1666555444.333222: invalid character '<' looking for beginning of value after 1 attempts

Desktop (please complete the following information):

• OS: Windows

Additional context
Add any other context about the problem here.

[rusq]

No response from the reporter.