FunctionClauseError for Macro.define_alias when typing an `alias Foo`

[mhanberg]

Description

MacroEnv.define_alias will error when you are actively typing an alias, as it is attempting to pass a "function call" to it.

This happens because we inject the cursor as __cursor__() into the source code, but that is not accurate. The same thing would
happen if you actually had typed a function call there.

Need to be more strict when expanding that part.