This message is harmless and can be ignored. It only means that some purely optional debugging and development-specific files are not available (because we do not publish them to the CDN). In more recent versions of Bokeh the requests have been suppressed, so that those log messages no longer appear. Regardless, these source map files are not required, and their absence does not affect or disrupt Bokeh in any way. Whatever caused your change/breakage, it is not related to this.
See, e.g. these messages show up even in the old version docs site, but the content still displays correctly: