Error in Saving Page

I have created a new block for responsive bootstrap image the code for it is as follows

{{#compare uni_link_to '==' Custom URL}}<a href="{{uni_custom_link}}">{{/compare}}{{#compare uni_link_to '==' Image}}<a href="{{uni_upload_image.url}}">{{/compare}}<img class="img-fluid {{uni_extra_image_classes}}" src="{{uni_upload_image.url}}" alt="{{#if uni_custom_alt_tag}}{{uni_custom_alt_tag}}{{else}}{{uni_upload_image.alt}}" />{{#compare uni_link_to '!=' None}}</a>{{/compare}}

I think I am doing something wrong in the code , that is why when I use the block in a page and try to publish the post, its not saving and throwing error “Publishing failed”

Can you please help me with what doing wrong for html output? I think I am not using the compare tag correctly ? the field “uni_link_to” is a select field, can I use something like uni_link_to.value to get its value and then compare it with a constant text ?