https://wordpress.org/support/plugin/quick-debug-log-viewer/
[Quick debug.log Viewer] Support | WordPress.org
debug log viewersupport wordpressquick
https://www.hanselman.com/blog/back-to-basics-using-fusion-log-viewer-to-debug-obscure-loader-errors/comments
Back to Basics: Using Fusion Log Viewer to Debug Obscure Loader Errors - Scott Hanselman's Blog
UPDATE: There is a new modern open source alternative to Fusion Log Viewer ...