If the placement area (right click) is 1x1 or 1 tile-wide, the following error occurs:

The mod Greeble (0.0.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event greeble::on_player_reverse_selected_area (ID 196)
__greeble__/pattern_gen/wfc/wfc.lua:340: attempt to index local 'chunkToSolve' (a nil value)
stack traceback:
    __greeble__/pattern_gen/wfc/wfc.lua:340: in function '_solveAttempt'
    __greeble__/pattern_gen/wfc/wfc.lua:439: in function 'cycleFunc'
    __greeble__/pattern_gen/wfc/wfc.lua:513: in function 'solve'
    __greeble__/pattern_gen/run.lua:131: in function 'testRun'
    __greeble__/control.lua:78: in function <__greeble__/control.lua:71>