Fix crashes on scene startup

[YakoYakoYokuYoku]

ReleaseNote

Compatibility (major, minor, patch, build): build
Jira ticket: N/A
Release Notes Comment: Fix crashes when simplyfing spaces with empty strings and using empty temporary dirs.

Special Notes:

Look or Scene Setup Change: No

Reviewers

N/A.

Pull request comments

Passing an empty string to replaceBlankToSingleSpace results in a failed assertion when calling result.back, so it'd be preferable to return early instead.

When a temporary dir is not set for getTmpDir Moonray is also going to crash with tmpDir.back, rather than that let's put a default value when is empty.

Rats test images

N/A.

Documentation (link)

N/A.

Unit Test Reminder

N/A.