From da25f4fed2627087a3a97420759b7223cbc3e881 Mon Sep 17 00:00:00 2001
From: Dave Clark <me@clarkdave.net>
Date: Wed, 13 Mar 2019 10:52:41 +0000
Subject: [PATCH] Prevent error if property block has no value (level 0)
 (#1061)

The tokenizer will parse a property like `width: ;`, but the property
helper for level 0 (i.e. minification only) was not accounting for
properties without a value and would throw a TypeError if the value
was missing

With this change, the property helper now checks for a missing property
value before trying to access it
---
 lib/writer/helpers.js                        | 8 ++++++--
 test/optimizer/level-0/optimizations-test.js | 8 ++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/lib/writer/helpers.js b/lib/writer/helpers.js
index 11727402c..6cbb54074 100644
--- a/lib/writer/helpers.js
+++ b/lib/writer/helpers.js
@@ -77,7 +77,9 @@ function lastPropertyIndex(tokens) {
 function property(context, tokens, position, lastPropertyAt) {
   var store = context.store;
   var token = tokens[position];
-  var isPropertyBlock = token[2][0] == Token.PROPERTY_BLOCK;
+
+  var propertyValue = token[2];
+  var isPropertyBlock = propertyValue && propertyValue[0] === Token.PROPERTY_BLOCK;
 
   var needsSemicolon;
   if ( context.format ) {
@@ -111,7 +113,9 @@ function property(context, tokens, position, lastPropertyAt) {
     case Token.PROPERTY:
       store(context, token[1]);
       store(context, colon(context));
-      value(context, token);
+      if (propertyValue) {
+        value(context, token);
+      }
       store(context, needsSemicolon ? semicolon(context, Breaks.AfterProperty, isLast) : emptyCharacter);
       break;
     case Token.RAW:
diff --git a/test/optimizer/level-0/optimizations-test.js b/test/optimizer/level-0/optimizations-test.js
index 7fa74a633..c86166b19 100644
--- a/test/optimizer/level-0/optimizations-test.js
+++ b/test/optimizer/level-0/optimizations-test.js
@@ -11,4 +11,12 @@ vows.describe('level 0')
       ]
     }, { level: 0 })
   )
+  .addBatch(
+    optimizerContext('empty properties', {
+      'are written': [
+        'a{color:#f00;font-weight:;background:red}',
+        'a{color:#f00;font-weight:;background:red}'
+      ]
+    }, { level: 0 })
+  )
   .export(module);