Python:
if expression:
statement(true)
else:
statement(false)
anotherStatement(bleh)
What can possibly be wrong with this? If the first four lines are using spaces and the last line is using a tab, that last statement will not execute as part of the else, but every time whether expression is true or false. Python should decide, spaces or tabs and throw an error if you mix them.
I see Python 3 doesn't allow mixing tabs and spaces, older versions of Python 2 which I used didn't even give as much as a warning and strange things would happen in the code.