Revert "wit/bindgen: create Go packages on-demand"

This reverts commit d4d2321.

Author: ydnar

wit/bindgen/generator.go

@@ -227,6 +227,11 @@ func (g *generator) define(dir wit.Direction, v wit.Node) (defined bool) {
 func (g *generator) defineWorlds() error {
 	g.opts.logger.Infof("Generating Go for %d world(s)\n", len(g.res.Worlds))
 	for _, w := range g.res.Worlds {
+		// Define a Go package for every world, regardless of use
+		_, err := g.newPackage(w, nil, "")
+		if err != nil {
+			return err
+		}
 		if w == g.world || g.world == nil {
 			err := g.defineWorld(w)
 			if err != nil {
@@ -2284,17 +2289,9 @@ func (g *generator) cgoFileFor(owner wit.TypeOwner) *gen.File {
 
 func (g *generator) packageFor(owner wit.TypeOwner) *gen.Package {
 	pkg := g.witPackages[owner]
-	if pkg != nil {
-		return pkg
-	}
-	var err error
-	switch owner := (owner).(type) {
-	case *wit.World:
-		pkg, err = g.newPackage(owner, nil, "")
-	}
 	if pkg == nil {
-		panic(fmt.Sprintf("BUG: cannot create Go package for wit.TypeOwner %s (%T: %p): %v",
-			owner.WITPackage().Name.String(), owner, owner, err))
+		panic(fmt.Sprintf("BUG: nil package for wit.TypeOwner %s (%T: %p)",
+			owner.WITPackage().Name.String(), owner, owner))
 	}
 	return pkg
 }