No bug, only unpleasant default setting.
At some time a ERC-check was introduced to check if a symbol also contains a simulation model. Useful for the people who use the simulation-feature.
Sadly this ERC-check was added with violation-severity set to error.
Just switch off this check:
schematic setup–>Electrical Rules–>Violation Severity–>section miscellaneous–>SPICE model issue
Setting will be saved with your project (so maybe you have to do this for multiple projects).
additional hint:
if you right-click on a ERC/DRC-error-headline you get a context-menu where you individually can change this specific error-type (see picture).
disadvantage for the first time: you still don’t know how the specific error-check is named in the preferences-severity dialog.
A visible checkbox in that window would make more sense, in this case.
Kicad is essentially a tool for making PCBs, it was later considered interesting for simulation since Kicad schematics are a good visible way to handle circuits instead of text files only.
Most of the time, and since the Kicad does not have a Simulation lib built in, the simulation is just an alternative use of Kicad. So I understand that the simulation check should not disrupt its use in the first place, especially when making the ERC.
But a visible checkbox that is unchecked by default. Could be a good solution.