fix 'cd falsepages' command issue

[eoneill]

#91 introduced a bug if nextAppSettings.srcDirectory === false (default)

This results in the command being evaluated as cd falsepages (instead of the expected cd pages).

The fix is simple, use a ternary instead of conditional chaining.

This bug appears to affect vantage-next at v1.0.4 and v1.0.5.