<pre>
func main() { … }
</pre>

<p>
Program execution begins by initializing the main package and then
invoking the function <code>main</code>.
When that function invocation returns, the program exits.
It does not wait for other (non-<code>main</code>) goroutines to complete.
</p>

<h2 id="Errors">Errors</h2>

<p>
The predeclared type <code>error</code> is defined as
</p>

<pre>

	defer func() {
		s := recover()
		if s == nil {
			t.Fatal("did not panic")
		}
		if s.(string) != "callback panic" {
			t.Fatal("wrong panic:", s)
		}
		if lockedOSThread() {
			t.Fatal("locked OS thread on exit from TestCallbackPanic")
		}
	}()
	nestedCall(func() { panic("callback panic") })
	panic("nestedCall returned")
}

func testCallbackPanicLoop(t *testing.T) {
	// Make sure we don't blow out m->g0 stack.