julia> plot(sinpi, -2, 2)
ERROR: BoundsError()
in showdot at /Users/stefan/.julia/TextPlots/src/plot.jl:47
in plot at /Users/stefan/.julia/TextPlots/src/plot.jl:82
in plot at /Users/stefan/.julia/TextPlots/src/plot.jl:127
I ran into this occasionally too. I never did come up with a solution I liked for handling values at the boundaries of the graph, but this cheap hack handles all the cases I know of.