permalink: false will break transform functions as implemented like example in docs, since outputPath is 'false'

[ckot]

Describe the bug

I recently added permalink: false to some templates and my transform function blew up an exception (listed below in screenshots section)

To Reproduce

1. add the following transform function (example from docs)

const htmlmin = require("html-minifier");

module.exports = function(eleventyConfig) {
  eleventyConfig.addTransform("htmlmin", function(content, outputPath) {
    if( outputPath.endsWith(".html") ) {
      let minified = htmlmin.minify(content, {
        useShortDoctype: true,
        removeComments: true,
        collapseWhitespace: true
      });
      return minified;
    }

    return content;
  });
};

2. add permalink: false to some template's data

Expected behavior

I'd expect that the content with permalink: false and for my transform function to work normally

Screenshots

$ eleventy
Writing dist/index.html from ./src/index.njk.
Error writing templates: (more in DEBUG output)
> Having trouble writing template: false

TemplateWriterWriteError was thrown
> outputPath.endsWith is not a function

TypeError was thrown:
TypeError: outputPath.endsWith is not a function
at Template. (/home/ckot/projects/work/11ty_test/.eleventy.js:7:24)
at Template.runTransforms (/usr/lib/node_modules/@11ty/eleventy/src/Template.js:387:29)
at Template.renderPageEntry (/usr/lib/node_modules/@11ty/eleventy/src/Template.js:548:28)
at process._tickCallback (internal/process/next_tick.js:68:7)
Problem writing Eleventy templates: (more in DEBUG output)

Environment:

• OS and version: Ubuntu LTS 18.04
• Eleventy Version: 0.10.0

Additional context

I suppose this is not a code bug but rather a documentation bug, although perhaps thinks which have permalink-false should't be passed through transforms, as they don't have an outputPath to begin with.

My fix was to simply test that outputPath is truthy, and that it's a string, prior to calling a string method on it. Regardless of whether there is a code fix for this, it would probably be good that the docs should look more like my solution, simply since it uses defensive programming.

const htmlmin = require("html-minifier");

module.exports = function(eleventyConfig) {
  eleventyConfig.addTransform("htmlmin", function(content, outputPath) {
   // test that outputPath is a string prior to doing anything with it.  setting permalink: false, will
   // set outputPath to 'false', and perhaps other settings may give unexpected outputPath values 
   if( outputPath && "string" === typeof(outputPath) && outputPath.endsWith(".html") ) {
      let minified = htmlmin.minify(content, {
        useShortDoctype: true,
        removeComments: true,
        collapseWhitespace: true
      });
      return minified;
    }

    return content;
  });
};

[chrissy-dev]

Just to note I had the same issue as @ckot has mentioned, I used a similar workaround/fix.

[zachleat]

This is a duplicate of #653—please follow along over there!