I can confirm that the released version of TotalSpaces2 does not work with macOS Mojave 10.14.4, and repeatedly crashes Dock with the ‘FastSwitch2 plug-in’ every 1 seconds.
Disabling TotalSpaces2 allows the desktop to load, Dock stops crashing, and the system functions… without TotalSpaces2 running.
Process: Dock 
Version: 1.8 (1963.5)
Build Info: Dock-1963005000000000~94
Code Type: X86-64 (Native)
Parent Process: ??? 
Responsible: Dock 
User ID: 501
PlugIn Path: /Applications/TotalSpaces2.app/Contents/Resources/TotalSpaces.bundle/Contents/MacOS/FastSwitch2
PlugIn Identifier: com.binaryage.FastSwitch2
PlugIn Version: 2.7.6 (2.7.6)
Date/Time: 2019-03-31 10:52:14.519 -0400
OS Version: Mac OS X 10.14.4 (18E226)
Report Version: 12
Anonymous UUID: 0AB038C4-4215-AB54-BC41-7BDB6FF56653
Is there an update to TotalSpaces2 that will address this new issue in 10.14.4?
Update: I just installed the beta listed above in this thread, and it appears to work. I’ll continue to test and reply back with any odd results I might find.