ignore empty documents produced by stylus-lang bug

background/background-worker.js

@@ -37,7 +37,7 @@ function compileUsercss(preprocessor, code, vars) {
   const builder = getUsercssCompiler(preprocessor);
   vars = simpleVars(vars);
   return Promise.resolve(builder.preprocess ? builder.preprocess(code, vars) : code)
-    .then(code => parseMozFormat({code}))
+    .then(code => parseMozFormat({code, emptyDocument: preprocessor === 'stylus'}))
     .then(({sections, errors}) => {
       if (builder.postprocess) {
         builder.postprocess(sections, vars);

js/moz-parser.js

@@ -7,10 +7,12 @@
  * Puts the global comments into the following section to minimize the amount of global sections.
  * Doesn't move the comment with ==UserStyle== inside.
  * @param {string} code
+ * @param {boolean} emptyDocument - https://github.com/stylus/stylus/issues/2415,
+ * TODO: update stylus-lang and remove emptyDocument everywhere
  * @param {number} styleId - used to preserve parserCache on subsequent runs over the same style
  * @returns {{sections: Array, errors: Array}}
  */
-function parseMozFormat({code, styleId}) {
+function parseMozFormat({code, emptyDocument, styleId}) {
   const CssToProperty = {
     'url':        'urls',
     'url-prefix': 'urlPrefixes',
@@ -18,7 +20,7 @@ function parseMozFormat({code, styleId}) {
     'regexp':     'regexps',
   };
   const hasSingleEscapes = /([^\\]|^)\\([^\\]|$)/;
-  const parser = new parserlib.css.Parser({starHack: true});
+  const parser = new parserlib.css.Parser({starHack: true, emptyDocument});
   const sectionStack = [{code: '', start: 0}];
   const errors = [];
   const sections = [];
@@ -70,6 +72,13 @@ function parseMozFormat({code, styleId}) {
     doAddSection(section);
   });
 
+  parser.addListener('emptydocument', e => {
+    const token = parser._tokenStream._token;
+    const section = sectionStack[sectionStack.length - 1];
+    section.code += mozStyle.slice(section.start, e.offset);
+    section.start = token.offset + token.value.length;
+  });
+
   parser.addListener('endstylesheet', () => {
     // add nonclosed outer sections (either broken or the last global one)
     const lastSection = sectionStack[sectionStack.length - 1];

js/usercss.js

@@ -71,7 +71,7 @@ const usercss = (() => {
       .then(({sections, errors}) => {
         if (!errors.length) errors = false;
         if (!sections.length || errors && !allowErrors) {
-          throw errors;
+          throw errors || 'Style does not contain any actual CSS to apply.';
         }
         style.sections = sections;
         return allowErrors ? {style, errors} : style;

vendor-overwrites/csslint/parserlib.js

@@ -3865,6 +3865,7 @@ self.parserlib = (() => {
      * @param {Boolean} [options.starHack] - allows IE6 star hack
      * @param {Boolean} [options.underscoreHack] - interprets leading underscores as IE6-7 for known properties
      * @param {Boolean} [options.ieFilters] - accepts IE < 8 filters instead of throwing syntax errors
+     * @param {Boolean} [options.emptyDocument] - accepts @document without {} block produced by stylus-lang
      */
     constructor(options) {
       super();
@@ -4333,6 +4334,11 @@ self.parserlib = (() => {
         functions.push(this._documentFunction());
       } while (stream.match(Tokens.COMMA));
 
+      this._ws();
+      if (this.options.emptyDocument && stream.peek() !== Tokens.LBRACE) {
+        this.fire({type: 'emptydocument', functions, prefix}, start);
+        return;
+      }
       stream.mustMatch(Tokens.LBRACE);
 
       this.fire({