Alexander,

You said:

Yes, the Strawberry 5.22 installer should not have damaged the existing 5.18.1 installation. It should have refused to install over 5.18.1, and instead give you instructions how to upgrade.

IMHO - That's the only statement of any importance. The install MSI can easily know that there is a previous version installed (the vast majority of cases will be an upgrade) and can either show a warning (and give them the option to ignore the warning) or stop the installation altogether (but, I don't like to force them). Furthermore, the MSI should provide hints as to what to do (e.g., use autobundle, then uninstall previous version). Considering the consequences, that seems like a reasonable addition to the MSI process.