Unable to see Manx session

[deacon-mp]

Hi,

When I was doing the user training in caldera, I faced issue while trying the manx related flag.

After pasting the manx sh tcp command in the calder server, I can see the agent entry under agents tab but unable to see the host under session also getting error "Error refreshing Manx"

Manx Command:
server="http://127.0.0.1:8888";socket="127.0.0.1:7010";contact="tcp";curl -s -X POST -H "file:manx.go" -H "platform:linux" $server/file/download > super_scary;chmod +x super_scary;./super_scary -http $server -socket $socket -contact $contact -v

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Migrated from mitre/caldera#3072

[deacon-mp]

Triage note: The "Error refreshing Manx" toast is caused by unhandled exceptions in the session endpoints in app/term_api.py. When the TCP handler encounters an error (e.g. the deprecated socket API issue described in #51), the sessions() and get_sessions() endpoints throw an unhandled exception that returns HTTP 500, triggering the error toast. Additionally, splash() could return None to the template causing the initial page render to fail.

PR #54 has been opened to fix the error handling in these endpoints so that the UI remains functional (showing an empty session list) even when the TCP backend has issues.

Note: for a full fix, PR #42 (fixing the underlying deprecated socket issue) should also be merged.