1501 - CompilerFamily '%s' is unrecognized.

Description
When the .CompilerFamily property is set to an unsupported value, Error #1501 will be emitted. For valid values, consult the Compiler() documentation.
Example
Config:
Compiler( 'compiler' ) { .Executable = 'compiler.exe' .CompilerFamily = 'xyz' }
Output:
c:\test\fbuild.bff(1,1): FASTBuild Error #1501 - Compiler() - .CompilerFamily 'xyz' is unrecognized. Compiler( 'compiler' ) ^ \--here
Fix:
Compiler( 'compiler' ) { .Executable = 'compiler.exe' .CompilerFamily = 'custom' }