Invalid string concatenation breaks Lodash _.template method

[filmic]

Minifing the Lodash library using Babili 0.0.11 breaks the _.template method.

The string concatenation in that method (https://github.com/lodash/lodash/blob/4.17.4/lodash.js#L14748) is minified to contain extraneous escape characters.

Input:

source = 'function(' + (variable || 'obj') + ') {\n' +
        (variable
          ? ''
          : 'obj || (obj = {});\n'
        ) +
        "var __t, __p = ''" +
        (isEscaping
           ? ', __e = _.escape'
           : ''
        ) +
        (isEvaluating
          ? ', __j = Array.prototype.join;\n' +
            "function print() { __p += __j.call(arguments, '') }\n"
          : ';\n'
        ) +
        source +
        'return __p\n}';

Output:
source='function('+(variable||'obj')+') {\n'+(variable?'':'obj || (obj = {});\n')+'var __t, __p = \'\''+(isEscaping?', __e = _.escape':'')+(isEvaluating?', __j = Array.prototype.join;\\nfunction print() { __p += __j.call(arguments, \\\'\\\') }\\n':';\n')+source+'return __p\n}';

Notice extra escape in \\n which results in \n in function body after Array.prototype.join:
... Array.prototype.join; \nfunction print() {...

That causes SyntaxError: Invalid or unexpected token when function is executed.

[filmic]

Other escaping related issue: #440

[filmic]

@boopathi Any hint when this will be fixed?
It is a blocker for anyone using Lodash template method i.e. in Backbone project.

[vigneshshanmugam]

@filmic Should be fixed once this PR #490 is merged