Get rid of checks when creating constructs. Check should handle this.

content.go

@@ -1,7 +1,5 @@
 package atom
 
-import "fmt"
-
 const (
 	InlineText = iota
 	InlineXHTML
@@ -17,17 +15,17 @@ type Content interface {
 }
 
 // NewContent creates a new Content. It returns a Content and an error.
-func NewContent(contentType int, mediaType string, content any) (Content, error) {
+func NewContent(contentType int, mediaType string, content any) Content {
 	switch contentType {
 	case 0:
-		return newInlineTextContent(mediaType, content)
+		return newInlineTextContent(mediaType, content.(string))
 	case 1:
-		return newInlineXHTMLContent(mediaType, content)
+		return newInlineXHTMLContent(mediaType, content.(*XHTMLDiv))
 	case 2:
 		return newInlineOtherContent(mediaType, content)
 	case 3:
-		return newOutOfLineContent(mediaType, content)
+		return newOutOfLineContent(mediaType, content.(string))
 	default:
-		return nil, fmt.Errorf("error creating new content: %v is not a valid text type", contentType)
+		return nil
 	}
 }