Console error favicon.png (localhost), & Failed to load resource

[mikehoffms]

Maybe only occurs on localhost, not gh.io.
Maybe my fork was behind, when seeing the old favico.png error in Console.

Encountered during creating PR #135 samples. Kept having to Clear Console Messages to make the Console tab clean, to get rid of an irrelevant error about favicon.png.

The issue repros in at least one of these samples (or, it did, in localhost):
#135 --

New sample	Demo URL	favico.png error?
/at-rules-font-palette-values/	https://microsoftedge.github.io/Demos/at-rules-font-palette-values/	Failed to load resource: the server responded with a status of 404 () - this error went away after super refresh.
/at-rules-position-try/	https://microsoftedge.github.io/Demos/at-rules-position-try/	ok
/at-rules-property/	https://microsoftedge.github.io/Demos/at-rules-property/	ok
/at-rules-scope/	https://microsoftedge.github.io/Demos/at-rules-scope/	ok
/at-rules-supports/	https://microsoftedge.github.io/Demos/at-rules-supports/	ok
/cascade-layers/	https://microsoftedge.github.io/Demos/cascade-layers/	ok
/emulate-focused-page/	https://microsoftedge.github.io/Demos/emulate-focused-page/	ok
/highlight-pseudo-elements/	https://microsoftedge.github.io/Demos/highlight-pseudo-elements/	ok

Screenshots showing various errors to fix in Console:

https://microsoftedge.github.io/Demos/at-rules-font-palette-values/
"Failed to load resource: the server responded with a status of 404 ()"

Error didn't occur after did:
In Edge, F12 (DevTools) > Right-click Refresh > Empty cache and hard refresh > F12.