speaker.playSound returns true when it should not

[Jeuvke]

local speaker = peripheral.find("speaker")
print(speaker.playSound("notasound"))

will return true.
playSound will never return false, and only throws when using capital letters, some special characters, or spaces in the sound name.

[SquidDev]

This is sadly unavoidable. We've got to choose between playing modded sounds (see dan200/ComputerCraft#578) or returning something useful, and we went for the former.