We recently observed errors in BUI, which reports require.js file is missing from path /AgentWeb/libs/require/require.js?

Environment: 
Agent Browser User UI (BUI) extensibility framework, BUI updates

Issue: 

After the BUI update, my extension is failing to work as expected.

Resolution:  

The extensions are referring to require.js from Product's library path (/AgentWeb/libs/require/require.js). This should never be done for extensions as it can change with any product change.  Instead; create a require.js file as a library; then import that library where needed in your BUI extensions.
Answer: Answer: Working with Library Extensions in BUI Extensibility Framework

Note: 

Further information on why an extension may fail can be found here. 
Answer: BUI extension is failing to work after updateBUI extension is failing to work after update