Clarify the error message for FileWatcherTests
Clarify the error message for FileWatcherTests

fable-compiler/Fable,fable-compiler/Fable,fable-compiler/Fable,fable-compiler/Fable,ncave/Fable,ncave/Fable,fable-compiler/Fable,fable-compiler/Fable,ncave/Fable,ncave/Fable,ncave/Fable,fable-compiler/Fable,ncave/Fable,ncave/Fable