This error has nothing to do with your current problem. For explanation: The browser tries to load a MAP file for each JS file. This is needed to display correct line numbers for compressed JS or TS files. If the browser doesn't find the MAP file, it gives an error.
As written: The browser message regarding the missing MAP file has nothing to do with the SpiderBasic map commands.
Thanks for the information. What can cause the problem? In an earlier version of the project the message does not appear.
I will test the project with other browsers. Maybe there will be some more information.
Or switch from Map to Linked List for testing.