Zero assertions is reported as "Cannot perform request" with exit 93

[korya]

Problem

Running with no assertion flags produces a network-failure-flavoured error and the network-failure exit code, even though the condition is detected before any request is attempted.

Reproduction

$ http-assert http://127.0.0.1:8791/ok

Error: Cannot perform request: no assertions defined
[exit=93]

Also reachable via --assert-body-empty=false, which parses to zero assertions.

Why it matters

This is a usage error. Reporting it as 93 means a CI job cannot distinguish "I forgot a flag" from "the endpoint is unreachable".

Suggested fix

Validate in parseAssertionFlags / the cobra Run before constructing the request, exit with the invalid-arguments code, and point at a remedy:

Error: no assertions specified; pass at least one --assert-* flag (e.g. --assert-ok)