The nRF Connect extension configures the C/C++ extension's IntelliSense context based on the active build configuration. When there was no active build configuration, the nRF Connect extension would previously leave the IntelliSense configuration blank, which caused a lot of errors in applications that were not built yet.
To provide a useful editing experience for C files ahead of the initial build, we have introduced a configuration that the IntelliSense engine can fall back to until the application is built for the first time. As the nRF Connect SDK's build system is completely dependent on the generated build output, some errors will still show up in the source files until the application is built, but most autocompletion and symbol location information should now be available.