E4020

Package not found in the loaded packages.

Erroneous Example

let a = @boolean.to_int(true)

The example above tries to call the method to_int in a package boolean, but this package is not present in the list of loaded packages, giving the following error on line 1:

Package "boolean" not found in the loaded packages.

Suggestion

Make sure the package name is valid.

If it is an external package, make sure that it is mentioned as one of the imported packages in moon.pkg.json as well.

In the above example, the package name should be @bool instead of @boolean:

let a = @bool.to_int(true)