What's alt+spacebar character and how to disable it?
Solution 1:
optionspace inserts a non-breaking space (NBSP, U+00A0) by default.
What I've done I've set my editor highlight the non-breaking space, so that I see when I accidentally enter it.
You could remap ⌥␣ to a normal space by creating ~/Library/KeyBindings/ and saving a property list like this as DefaultKeyBinding.dict:
{
"~ " = (insertText:, " ");
}