diff --git a/web/base_viewer.js b/web/base_viewer.js index 36c63cba0..a151a8673 100644 --- a/web/base_viewer.js +++ b/web/base_viewer.js @@ -150,8 +150,10 @@ class BaseViewer { ) { if ( !( - this.container instanceof HTMLDivElement && - this.viewer instanceof HTMLDivElement + this.container && + this.container.tagName.toUpperCase() === "DIV" && + this.viewer && + this.viewer.tagName.toUpperCase() === "DIV" ) ) { throw new Error("Invalid `container` and/or `viewer` option.");