If anything goes wrong, './fips clean all' and './fips diag' are the two most useful commands.
'./fips clean all' deletes all build files created by fips and thus resets a project into a clean starting state.
'./fips diag' runs a number of diagnostic tests and provides useful error output:
'./fips diag tools' tests whether additional 3rd party tools are present, and if not found, explains whether the tools are required or optional, and what they are needed for.
'./fips diag fips' simply checks whether fips itself is up-to-date. If not, simply run a 'git pull' from within the fips directory to get the latest version.
'./fips diag configs' goes through all existing build config files, checks if their content is valid, and whether all required prerequisites are met in the current environment to build them (e.g. wether the required build tools exist and cross-platform SDKs have been installed):