blueprint: remove unused error

It was moved to the distro package a while ago.

internal/blueprint/blueprint.go

@@ -1,16 +1,6 @@
 // Package blueprint contains primitives for representing weldr blueprints
 package blueprint
 
-// An InvalidOutputFormatError is returned when a requested output format is
-// not supported. The requested format is included as the error message.
-type InvalidOutputFormatError struct {
-	message string
-}
-
-func (e *InvalidOutputFormatError) Error() string {
-	return e.message
-}
-
 // A Blueprint is a high-level description of an image.
 type Blueprint struct {
 	Name           string          `json:"name"`

internal/blueprint/blueprint_test.go

@@ -1,27 +0,0 @@
-package blueprint_test
-
-import (
-	"testing"
-
-	"github.com/osbuild/osbuild-composer/internal/blueprint"
-)
-
-func TestInvalidOutputFormatError_Error(t *testing.T) {
-	tests := []struct {
-		name string
-		want string
-	}{
-		{
-			name: "basic",
-			want: "",
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			e := &blueprint.InvalidOutputFormatError{}
-			if got := e.Error(); got != tt.want {
-				t.Errorf("InvalidOutputFormatError.Error() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}