Unexpected UnaryExpression. Expected an Identifier

[jbt]

I'm seeing the above error when I have lots of nested if/else's with the occasional empty block.

Stack trace if it's useful

Error: test.js: Unexpected UnaryExpression. Expected an Identifier
    at Mangler.renameNew (foo/node_modules/babel-plugin-minify-mangle-names/lib/index.js:193:19)
    at foo/node_modules/babel-plugin-minify-mangle-names/lib/index.js:143:23
    at Array.map (native)
    at Scopable (foo/node_modules/babel-plugin-minify-mangle-names/lib/index.js:135:16)
    at NodePath._call (foo/node_modules/babel-traverse/lib/path/context.js:76:18)
    at NodePath.call (foo/node_modules/babel-traverse/lib/path/context.js:48:17)
    at NodePath.visit (foo/node_modules/babel-traverse/lib/path/context.js:105:12)
    at TraversalContext.visitQueue (foo/node_modules/babel-traverse/lib/context.js:150:16)
    at TraversalContext.visitMultiple (foo/node_modules/babel-traverse/lib/context.js:103:17)
    at TraversalContext.visit (foo/node_modules/babel-traverse/lib/context.js:190:19)

Minimum example I could come up with (repl)

function foo() {
  var a, b, c;

  if (a) {
    if (b) {
      if (c) {}
    }
  } else {
    if (b) {
    } else {
      if (c) {}
    }
  }
}

Seems to be coming from the interaction of minify-dead-code-elimination and minify-mangle-names (both seem fine individually but fail when used together)

Error's being thrown here which suggests it might be an upstream Babel bug?

[boopathi]

Thanks for reporting.

It's an issue with mangler. Will take a look.

[jbt]

Nice one! 👍