feat(渲染逻辑): 完善图片另存与缺字体处理

ofdgo_renderer_font_loader_canvas.go

@@ -14,11 +14,7 @@
 
 package ofdgo
 
-import (
-	"fmt"
-
-	"github.com/tdewolff/canvas"
-)
+import "github.com/tdewolff/canvas"
 
 // loadFont 加载字体
 // 入参: fontID 字体ID
@@ -34,13 +30,6 @@ func (r *Renderer) loadFont(fontID string) *canvas.FontFamily {
 	}
 	of := r.Reader.fontCache[fontID]
 	if len(resolved.Data) == 0 {
-		if !r.textOnly {
-			name := fontID
-			if of != nil && of.FontName != "" {
-				name = of.FontName
-			}
-			r.renderError = fmt.Errorf("font %q is unavailable", name)
-		}
 		return nil
 	}
 	if of == nil {