show source code in build error when updating

fixes #891

background/update-manager.js

@@ -78,17 +78,17 @@ const updateMan = (() => {
 
   /**
    * @param {{
-      id?: number
-      style?: StyleObj
-      port?: chrome.runtime.Port
-      save?: boolean = true
-      ignoreDigest?: boolean
+      id?: number,
+      style?: StyleObj,
+      port?: chrome.runtime.Port,
+      save?: boolean,
+      ignoreDigest?: boolean,
     }} opts
    * @returns {{
-      style: StyleObj
-      updated?: boolean
-      error?: any
-      STATES: UpdaterStates
+      style: StyleObj,
+      updated?: boolean,
+      error?: any,
+      STATES: UpdaterStates,
      }}
 
    Original style digests are calculated in these cases:
@@ -127,7 +127,7 @@ const updateMan = (() => {
         err && err.message ||
         err;
       res = {error, style, STATES};
-      state = `${STATES.SKIPPED} (${error})`;
+      state = `${STATES.SKIPPED} (${Array.isArray(err) ? err[0].message : error})`;
     }
     log(`${state} #${id} ${style.customName || style.name}`);
     if (port) port.postMessage(res);

js/csslint/parserlib.js

@@ -2047,6 +2047,7 @@ self.parserlib = (() => {
       this.name = this.constructor.name;
       this.col = pos.col;
       this.line = pos.line;
+      this.offset = pos.offset;
       this.message = message;
     }
   }
@@ -2056,6 +2057,7 @@ self.parserlib = (() => {
       super();
       this.col = pos.col;
       this.line = pos.line;
+      this.offset = pos.offset;
       this.message = message;
     }
   }
@@ -3462,7 +3464,7 @@ self.parserlib = (() => {
      * @param {string|Object} event
      * @param {parserlib.Token|SyntaxUnit} [token=this._tokenStream._token] - sets the position
      */
-    fire(event, token = this._tokenStream._token) {
+    fire(event, token = event.offset != null ? event : this._tokenStream._token) {
       if (typeof event === 'string') {
         event = {type: event};
       }

js/moz-parser.js

@@ -83,6 +83,12 @@ function extractSections({code, styleId, fast = true}) {
 
   parser.addListener('error', e => {
     errors.push(e);
+    const min = 5; // characters to show
+    const max = 100;
+    const i = e.offset;
+    const a = Math.max(mozStyle.lastIndexOf('\n', i - min) + 1, i - max);
+    const b = Math.min(mozStyle.indexOf('\n', i - a > min ? i : i + min) + 1 || 1e9, i + max);
+    e.context = mozStyle.slice(a, b);
   });
 
   try {

manage/updater-ui.js

@@ -137,7 +137,6 @@ function reportUpdateState({updated, style, error, STATES}) {
       error === STATES.SAME_VERSION
     );
     const edited = error === STATES.EDITED || error === STATES.MAYBE_EDITED;
-    entry.dataset.error = error;
     if (!error) {
       error = t('updateCheckFailServerUnreachable') + '\n' + style.updateUrl;
     } else if (typeof error === 'number') {
@@ -149,7 +148,13 @@ function reportUpdateState({updated, style, error, STATES}) {
     } else if (typeof error === 'object' && error.message) {
       // UserCSS meta errors provide an object
       error = error.message;
+    } else if (Array.isArray(error)) {
+      // UserCSS build error
+      error = error.map(e => `${e.message || e}${
+        e.context ? '\n' + e.context.replace(/^/gm, '\t') : '' // indenting source text
+      }`).join('\n');
     }
+    entry.dataset.error = error;
     const message = same ? t('updateCheckSucceededNoUpdate') : error;
     newClasses.set('no-update', true);
     newClasses.set('update-problem', !same);