Catch and handle errors in pattern lab builds

[isaacchansky]

Description

When pattern lab builds break, error messages were being suppressed. This should surface them again.

Related Issue / Ticket

Steps to Test

1. add some malformed twig code to a twig file
2. run gulp
3. See the verbose error in the console

Screenshots

Use something like licecap to capture gifs to demonstrate behaviors.

Additional Notes:

Anything else to add?

Impacted Areas in Application

@todo

Today I learned...

[rbayliss]

Hey @isaacchansky, I checked this out and I'm not sure I understand what you're requesting. On the dev branch, If I run gulp and wait for the initial build to complete, then enter some invalid Twig into a template, I see the following errors in my console:

So it looks like the current state (on the dev branch) is that it's telling us when there's a fatal syntax error, although it does suppress the output of those non-fatal warnings until we hit a fatal error. Am I missing something?

[isaacchansky]

Interesting. So, on my machine if I add an unclosed IF statement to a twig file, I get the following on dev:

Browsersync] Reloading Browsers...
[22:21:53] Starting 'patternlab:build'...
[22:21:53] Starting 'patternlab:patterns'...
[22:21:55] 'patternlab:patterns' errored after 1.65 s
[22:21:55] Error: Command failed: php '/Users/isaacchansky/Clients/MassGov/mayflower/styleguide/core/console' --generate --patternsonly
 `php '/Users/isaacchansky/Clients/MassGov/mayflower/styleguide/core/console' --generate --patternsonly` (exited with error code 255)
    at callback (/Users/isaacchansky/Clients/MassGov/mayflower/styleguide/node_modules/child-process-promise/lib/index.js:33:27)
    at ChildProcess.exithandler (child_process.js:212:5)
    at emitTwo (events.js:106:13)
    at ChildProcess.emit (events.js:194:7)
    at maybeClose (internal/child_process.js:899:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:226:5)
[22:21:55] 'patternlab:build' errored after 1.65 s

And then on this branch for the PR I get:

Fatal error: Uncaught Twig_Error_Syntax: Unexpected end of template in "@atoms/decorative-link.twig" at line 9. in /Users/isaacchansky/Clients/MassGov/mayflower/styleguide/vendor/twig/twig/lib/Twig/TokenStream.php:59
Stack trace:
#0 /Users/isaacchansky/Clients/MassGov/mayflower/styleguide/vendor/twig/twig/lib/Twig/TokenParser/If.php(40): Twig_TokenStream->next()
#1 /Users/isaacchansky/Clients/MassGov/mayflower/styleguide/vendor/twig/twig/lib/Twig/Parser.php(187): Twig_TokenParser_If->parse(Object(Twig_Token))
#2 /Users/isaacchansky/Clients/MassGov/mayflower/styleguide/vendor/twig/twig/lib/Twig/Parser.php(100): Twig_Parser->subparse(NULL, false)
#3 /Users/isaacchansky/Clients/MassGov/mayflower/styleguide/vendor/twig/twig/lib/Twig/Environment.php(619): Twig_Parser->parse(Object(Twig_TokenStream))
#4 /Users/isaacchansky/Clients/MassGov/mayflower/styleguide/vendor/twig/twig/lib/Twig/Environment.php(671): Twig_Environment->parse(Object(Twig_TokenStream))
#5 /Users/isaacchansky/Clients/MassGov/mayflower/styleguide/vendor/twig/t in /Users/isaacchansky/Clients/MassGov/mayflower/styleguide/vendor/twig/twig/lib/Twig/TokenStream.php on line 59

So, the goal was to surface line numbers with errors in twig templates.

Likewise for JSON files, on dev if I have an unquoted attribute I get:

[22:26:20] Error: Command failed: php '/Users/isaacchansky/Clients/MassGov/mayflower/styleguide/core/console' --generate --patternsonly
 `php '/Users/isaacchansky/Clients/MassGov/mayflower/styleguide/core/console' --generate --patternsonly` (exited with error code 1)
    at callback (/Users/isaacchansky/Clients/MassGov/mayflower/styleguide/node_modules/child-process-promise/lib/index.js:33:27)
    at ChildProcess.exithandler (child_process.js:212:5)
    at emitTwo (events.js:106:13)
    at ChildProcess.emit (events.js:194:7)
    at maybeClose (internal/child_process.js:899:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:226:5)
[22:26:20] 'patternlab:build' errored after 535 ms

But on this branch for the PR I get:

The JSON file, decorative-link.json, wasn't loaded. The error: Syntax error, malformed JSON

Parse error on line 1:

^

(note: it always says line 1 due to what I assume is a lack of expansion on parsing, but you still get the file name).

[isaacchansky]

In case this is a machine setup difference:

$ node -v
v7.8.0

$ npm -v
4.2.0

$ gulp -v
[22:27:20] CLI version 2.0.1
[22:27:20] Local version 4.0.0

$ php -v
PHP 7.1.16 (cli) (built: Apr  1 2018 13:14:42) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2018 Zend Technologies