DiagnosticsError codes

M0023 import cycle

Two or more packages import each other.

Go does not allow import cycles. Move the shared code into a third package that both import.

The mistake and the fix

The mistake

// package a imports b, package b imports a

Fixed

// move what both need into package c; a and b import c

M0022 test failed

A test called t.Error, t.Fatal or panicked.

M0024 name not exported

The name exists in the package but starts with a lower case letter, so only that package can use it.