feat(ImageProvider): disable replace when detect empty image url

app/src/main/java/io/legado/app/ui/book/read/page/provider/ImageProvider.kt

@@ -114,6 +114,7 @@ object ImageProvider {
     ): Bitmap {
         //src为空白时 可能被净化替换掉了 或者规则失效
         if (book.getUseReplaceRule() && src.isBlank()) {
+           book.setUseReplaceRule(false)
            appCtx.toastOnUi(R.string.error_image_url_empty)
         }
         val vFile = BookHelp.getImage(book, src)