Compare selected versions of a page truncates after a malformed <img .. > tag

[Brett Hall]

The history comparison is broken by a bad img tag on our internal confluence site using Confluence 7.4.0.  When clicking the Page History for example v174 & 175 then pressing Compare Selected Versions, the page that is shown is truncated after this img tag that is missing the src element:

<img style="margin-left: 3.0px;width: 16.0px;height: 16.0px;"/>

I'm not sure where this came from, maybe a copy/paste issue. When I delete it, it's fine. 

The main issue for me is that it is only noticeable if you look carefully in edit mode and see an empty white box character. I wonder if anyone has suggestions how to catch these more easily, this evaded me for hours before I found it (ironically while researching this post)!