PlotGroups with heatmap - diff undefined

[SamGG]

Hi,
Many thanks for your invaluable packages.
Just a short alert. diff is undefined at

FlowSOM/R/3_buildMST.R

Line 1627 in af08bb6

annotation[[group]] <- values * (-1)^(diff < 0)

I feel you pushed a wip version of this function.
Cheers.