cajeta.session.PackageInstallException — a Packages.install that could not proceed. Subtype of RecoverableException, because a failed install leaves the session serving: catching one and carrying on is the expected thing to do.

import cajeta.session.Packages;

try {
    Packages.install("dev.cajeta.ml", "0.10.*");
} catch (PackageInstallException e) {
    String why = e.message;   // the session is still usable
}

What throws it

Cause
No live session	`install` was called somewhere with no session to install into — `cajeta run`, a compiled binary. Declare the dependency in `cajeta.json` instead
Nothing satisfies the constraint	The message names the constraint and every repository consulted
Version conflict	The archive is already loaded at a version this constraint excludes. A session cannot replace a loaded archive; the message says a restart is required
Checksum mismatch	The fetched bytes do not match the repository’s published sha256. They are discarded and nothing is installed
Signature rejected	The archive is signed, but by no key in the machine’s trust store — or it is signed and the machine trusts no keys at all, so the signature cannot be checked
`require-signatures`	The governing manifest requires a signature and the archive publishes none
Name collision	The archive declares a class the session already holds. An install never shadows session state
No governing project	`installAndSave` with no `cajeta.json` to write to

Methods

Signature
`PackageInstallException(#String message)` ⚑	Wrap a heap `#String` message naming what was rejected and why

Source: docs/stdlib/session/PackageInstallException.md · 1 min read · 246 words