Merge error on ValleyMorphTool on ArcMap 10.8.1

Hello there when I run the toolbox i'm getting such error which most likely related to python that has been used back then and also the version of ArcMap in which code might need an update about it. Do you have any idea about how this could be solved?

Executing: rivertransect "C:\Users**\Desktop\ValleyMorphTool-master\test\output.gdb" wsheddem wshedbound ID 50 500 # false Start Time: Tue Aug 30 23:47:52 2022 Running script rivertransect... gp.scratchworkspace = C:\Users**\AppData\Local\Temp\arcC300\rivertransect.gdb processing watershed ID 2182 (1 of 2) ... geometric network for streams created ... flags consisting of source and sink points created ... longest_riverline created ... Traceback (most recent call last): File "C:\Users**\Desktop\ValleyMorphTool-master\script\arctoolbox\river_transect.py", line 1844, in main(workspace, in_raster, watershedbound, watershedfid, widlist, interval, interval_profile, count_intervalpr, adjust_edge, count_interval) File "C:\Users**\Desktop\ValleyMorphTool-master\script\arctoolbox\river_transect.py", line 1732, in main rivercrosslines, midcrosslines, watershedmidline, longest_riverline, valleyfloor, elevationpoints, midcrosslinestable, elevtable, vfwtable = get_riverprofile(in_raster, "local_dem", "local_watershed", wid, interval, interval_profile, count_intervalpr, adjust_edge, count_interval) File "C:\Users**\Desktop\ValleyMorphTool-master\script\arctoolbox\river_transect.py", line 1632, in get_riverprofile longaxis = get_longaxis(reduced_raster, wid, lowpoint, farpoint) File "C:\Users**\Desktop\ValleyMorphTool-master\script\arctoolbox\river_transect.py", line 421, in get_longaxis endpoints = merge([lowpoint, farpoint], "myendpoints") File "C:\Users******\Desktop\ValleyMorphTool-master\script\arctoolbox\river_transect.py", line 382, in merge vt.addrow(input) RuntimeError: ERROR 999999: Error executing function

turugban / ValleyMorphTool

Merge error on ValleyMorphTool on ArcMap 10.8.1 #2