Left Clicking on https://meta.discourse.org/users/idontexist takes you to an error page, not the 404 page you get if you right-click and open in new tab or middle click the link.
Errors in Dev Console when left clicking
[object Object]Discourse.Route.extend.actions.error @ _application-ad8ffadeed762cdfb28b7fae4a9048bf.js:78237C @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:34235l @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:55158i.trigger @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:54983(anonymous function) @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:54788b @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:55600y @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:55612g @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:55583p @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:55525(anonymous function) @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:37309r.invoke @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:11597r.flush @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:11662n.flush @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:11467s.end @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:10892s.run @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:10947l @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:26183Discourse.Ajax.Em.Mixin.create.ajax.a.error @ _application-ad8ffadeed762cdfb28b7fae4a9048bf.js:83J.Callbacks.c @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:3364J.Callbacks.h.fireWith @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:3364r @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:3366J.ajaxTransport.Y.cors.e.crossDomain.send.t @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:3366
_vendor-cb7be21782ac642d67545fd3c9ee1618.js:37347 Error: Not Found
at o (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:37324)
at Object.e.default.trigger (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:56277)
at h._onerror (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:57291)
at p (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:55522)
at _vendor-cb7be21782ac642d67545fd3c9ee1618.js:37309
at r.invoke (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:11597)
at Object.r.flush (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:11662)
at Object.n.flush (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:11467)
at Object.s.end (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:10892)
at Object.s.run (_vendor-cb7be21782ac642d67545fd3c9ee1618.js:10947)o @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:37347e.default.trigger @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:56277h._onerror @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:57291p @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:55522(anonymous function) @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:37309r.invoke @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:11597r.flush @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:11662n.flush @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:11467s.end @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:10892s.run @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:10947l @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:26183Discourse.Ajax.Em.Mixin.create.ajax.a.error @ _application-ad8ffadeed762cdfb28b7fae4a9048bf.js:83J.Callbacks.c @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:3364J.Callbacks.h.fireWith @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:3364r @ _vendor-cb7be21782ac642d67545fd3c9ee1618.js:3366J.ajaxTransport.Y.cors.e.crossDomain.send.t @ _vendor-cb7be21782ac642d67545fd3c9ee161
Screenshot of error
Screenshot when Right-Clicking and opening in new tab or using middle click.