Merge pull request #26 from jjeffery/not-found-error

Return os.ErrNotExist if file not found

assetfs.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"strings"
 	"time"
 )
 
@@ -153,6 +154,12 @@ func (fs *AssetFS) Open(name string) (http.File, error) {
 	if children, err := fs.AssetDir(name); err == nil {
 		return NewAssetDirectory(name, children, fs), nil
 	} else {
+		// If the error is not found, return an error that will
+		// result in a 404 error. Otherwise the server returns
+		// a 500 error for files not found.
+		if strings.Contains(err.Error(), "not found") {
+			return nil, os.ErrNotExist
+		}
 		return nil, err
 	}
 }