Failed to load source map warnings on subfolder install

I have managed to install Discouse forum on subfolder (\forum) and everything works fine, except that I get a bunch of “DevTools failed to load source map:” warnings in Edge Developer Console.
When I have investigated I have found out that for example really contains sourceMappingURL=/assets/plugins/ (without forum).

How can we solve it? I have found that some others have reported the same issue, but no solution.
What are the functional consequences of this error?