Could not interpret API response: Failed to read JSON: expected value at line 1 column 1

[teto]

I wanted to check on my mujmap config, see if it was still functional but I get

mujmap sync -v  
error: Could not sync mail: Could not open remote session: Could not interpret API response: Failed to read JSON: expected value at line 1 column 1

with more output:

[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] Ticket saved
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] Ticket saved
[2024-11-21T19:06:59Z DEBUG ureq::unit] response 302 to GET https://jmap.fastmail.com/.well-known/jmap
[2024-11-21T19:06:59Z DEBUG ureq::unit] redirect 302 https://jmap.fastmail.com/.well-known/jmap -> https://www.fastmail.com/for-developers/
[2024-11-21T19:06:59Z DEBUG ureq::stream] dropping stream: TcpStream { addr: 10.0.0.127:54064, peer: 103.168.172.62:443, fd: 9 }
[2024-11-21T19:06:59Z DEBUG ureq::stream] connecting to www.fastmail.com:443 at 172.66.44.165:443
[2024-11-21T19:06:59Z DEBUG rustls::client::hs] No cached session for DnsName(DnsName(DnsName("www.fastmail.com")))
[2024-11-21T19:06:59Z DEBUG rustls::client::hs] Not resuming any session
[2024-11-21T19:06:59Z DEBUG rustls::client::hs] Using ciphersuite Tls13(Tls13CipherSuite { suite: TLS13_AES_256_GCM_SHA384, bulk: Aes256Gcm })
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] Not resuming
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] TLS1.3 encrypted extensions: [ServerNameAck]
[2024-11-21T19:06:59Z DEBUG rustls::client::hs] ALPN protocol is None
[2024-11-21T19:06:59Z DEBUG ureq::stream] created stream: TcpStream { addr: 10.0.0.127:58184, peer: 172.66.44.165:443, fd: 9 }
[2024-11-21T19:06:59Z DEBUG ureq::unit] sending request GET https://www.fastmail.com/for-developers/
[2024-11-21T19:06:59Z DEBUG ureq::unit] writing prelude: GET /for-developers/ HTTP/1.1
    Host: www.fastmail.com
    User-Agent: ureq/2.4.0
    Accept: */*
    accept-encoding: gzip
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] Ticket saved
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] Ticket saved
[2024-11-21T19:06:59Z DEBUG ureq::unit] response 302 to GET https://www.fastmail.com/for-developers/
[2024-11-21T19:06:59Z DEBUG ureq::unit] redirect 302 https://www.fastmail.com/for-developers/ -> https://www.fastmail.com/?pk_campaign=for-developers
[2024-11-21T19:06:59Z DEBUG ureq::stream] dropping stream: TcpStream { addr: 10.0.0.127:58184, peer: 172.66.44.165:443, fd: 9 }
[2024-11-21T19:06:59Z DEBUG ureq::stream] connecting to www.fastmail.com:443 at 172.66.44.165:443
[2024-11-21T19:06:59Z DEBUG rustls::client::hs] Resuming session
[2024-11-21T19:06:59Z DEBUG rustls::client::hs] Using ciphersuite Tls13(Tls13CipherSuite { suite: TLS13_AES_256_GCM_SHA384, bulk: Aes256Gcm })
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] Resuming using PSK
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] TLS1.3 encrypted extensions: []
[2024-11-21T19:06:59Z DEBUG rustls::client::hs] ALPN protocol is None
[2024-11-21T19:06:59Z DEBUG ureq::stream] created stream: TcpStream { addr: 10.0.0.127:58188, peer: 172.66.44.165:443, fd: 9 }
[2024-11-21T19:06:59Z DEBUG ureq::unit] sending request GET https://www.fastmail.com/?pk_campaign=for-developers
[2024-11-21T19:06:59Z DEBUG ureq::unit] writing prelude: GET /?pk_campaign=for-developers HTTP/1.1
    Host: www.fastmail.com
    User-Agent: ureq/2.4.0
    Accept: */*
    accept-encoding: gzip
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] Ticket saved
[2024-11-21T19:06:59Z DEBUG rustls::client::tls13] Ticket saved
[2024-11-21T19:06:59Z DEBUG ureq::unit] response 200 to GET https://www.fastmail.com/?pk_campaign=for-developers
[2024-11-21T19:06:59Z DEBUG ureq::stream] dropping stream: TcpStream { addr: 10.0.0.127:58188, peer: 172.66.44.165:443, fd: 9 }
error: Could not sync mail: Could not open remote session: Could not interpret API response: Failed to read JSON: expected value at line 1 column 1

I find the [2024-11-21T19:06:59Z DEBUG ureq::unit] redirect 302 https://www.fastmail.com/for-developers/ -> https://www.fastmail.com/?pk_campaign=for-developers mention a bit weird.