Bug: Invalid semi-colon in edge cases

[loilo]

I couldn't even find a proper descriptive title for this.

So, trying to squash minified AdapterJS revealed another problem.

Boiled down to the essence, the following code generates invalid JavaScript:

function fn () {
  if ( any_condition )
    global_variable = true;
  else
    var local_variable = true;
}

The invalid output is the following:

function fn(){any_condition&&(global_variable=!0;)}
                           // invalid semicolon ^

This will only happen (list may not be exhaustive) if:

• The assigned variable in the if block is global (also works with a property of a global object).
• The assignment in the if block ends with a semi-colon.
• An else block is present. Curly braces are optional.
• The else block only contains any of the following:
  • assignments to local variables ("local" in this context means that the declaration keyword (var, let, const) is inside the else block.
  • if/else blocks that only contain things from this list (recursion, yay!)
  • plain blocks { ... } with any content