What is likely happening is the binds for your movement keys are being overwritten by the trashcan script. The solution would normally be to find what your movement keys are bound to by the null movement script then replace the +forward, +back, +left, and +right in the binds in the trashcan script with their corresponding null movement script alias.
For some reason this didn't work for me when I had the same issue (could be some script issue or could just be my own stupidity) so I just ended up binding my forward/back and weapon switching keys to the trashcan script binds and used the null movement script binds for left and right. The easiest way to do this is to just find the binds for left and right in the null movement script and copy paste them to the very end of your autoexec. If you actually want the null-cancelling movement for forward and back this obviously doesn't work but I never really pressed W and S at the same time ever.