Better error when theme isn’t found

Author: andrewbranch

src/createGetRegistry.js

@@ -1,9 +1,7 @@
 // @ts-check
-const fs = require('fs');
 const { getGrammarLocation, getGrammar, getAllGrammars } = require('./storeUtils');
-const { promisify } = require('util');
+const { readFile } = require('./utils');
 const { Registry, parseRawGrammar } = require('vscode-textmate');
-const readFile = promisify(fs.readFile);
 
 function createEmitter() {
   /** @type {() => void} */

src/downloadExtension.js

@@ -1,8 +1,6 @@
 // @ts-check
 const fs = require('fs');
 const path = require('path');
-const zlib = require('zlib');
-const util = require('util');
 const processExtension = require('./processExtension');
 const { highestBuiltinLanguageId } = require('./storeUtils');
 const {
@@ -11,7 +9,6 @@ const {
   getExtensionBasePath,
   getExtensionPackageJson
 } = require('./utils');
-const gunzip = util.promisify(zlib.gunzip);
 let languageId = highestBuiltinLanguageId + 1;
 
 /**

src/host.js

@@ -1,8 +1,6 @@
 const request = require('request');
 const decompress = require('decompress');
-const zlib = require('zlib');
-const util = require('util');
-const gunzip = util.promisify(zlib.gunzip);
+const { gunzip } = require('./utils');
 
 /**
  * @typedef {object} Response

src/index.js

@@ -11,7 +11,7 @@ const { sanitizeForClassName } = require('./utils');
 const { loadColorTheme } = require('../lib/vscode/colorThemeData');
 const { getClassNameFromMetadata } = require('../lib/vscode/modes');
 const { downloadExtensionIfNeeded: downloadExtensionsIfNeeded } = require('./downloadExtension');
-const { getGrammar, getScope, getThemeLocation } = require('./storeUtils');
+const { getGrammar, getScope, ensureThemeLocation } = require('./storeUtils');
 const { generateTokensCSSForColorMap } = require('../lib/vscode/tokenization');
 const {
   renderRule,
@@ -227,9 +227,7 @@ function createPlugin() {
 
           const themeClassName = themeClassNames[setting];
           const themeCache = await cache.get('themes');
-          const colorThemePath =
-            getThemeLocation(colorThemeIdentifier, themeCache) ||
-            path.resolve(markdownNode.fileAbsolutePath, colorThemeIdentifier);
+          const colorThemePath = ensureThemeLocation(colorThemeIdentifier, themeCache, markdownNode.fileAbsolutePath);
 
           const { resultRules: tokenColors, resultColors: settings } = loadColorTheme(colorThemePath);
           const defaultTokenColors = {

src/storeUtils.js

@@ -1,5 +1,6 @@
 // @ts-check
 const path = require('path');
+const { exists } = require('./utils');
 // @ts-ignore
 const grammarManifest = require('../lib/grammars/manifest.json');
 // @ts-ignore
@@ -39,16 +40,25 @@ function getGrammarLocation(grammar) {
 /**
  *
  * @param {string} themeNameOrId
- * @param {*} themeCache
+ * @param {object} themeCache
+ * @param {string} markdownFilePath
  */
-function getThemeLocation(themeNameOrId, themeCache) {
+async function ensureThemeLocation(themeNameOrId, themeCache, markdownFilePath) {
   const themes = { ...themeManifest, ...themeCache };
   for (const themeId in themes) {
     const theme = themes[themeId];
     if (themeNameOrId === themeId || themeNameOrId.toLowerCase() === theme.label.toLowerCase()) {
-      return path.isAbsolute(theme.path) ? theme.path : path.resolve(__dirname, '../lib/themes', theme.path);
+      const themePath = path.isAbsolute(theme.path) ? theme.path : path.resolve(__dirname, '../lib/themes', theme.path);
+      if (!await exists(themePath)) {
+        throw new Error(`Theme manifest lists '${themeNameOrId}' at '${themePath}, but no such file exists.'`);
+      }
     }
   }
+
+  const locallyResolved = path.resolve(path.dirname(markdownFilePath), themeNameOrId);
+  if (!await exists(locallyResolved)) {
+    throw new Error(`Theme manifest does not contain theme '${themeNameOrId}', and no theme file exists at '${locallyResolved}'.`);
+  }
 }
 
 const highestBuiltinLanguageId = Object.keys(grammarManifest).reduce(
@@ -75,7 +85,7 @@ module.exports = {
   getScope,
   getGrammar,
   getGrammarLocation,
-  getThemeLocation,
+  ensureThemeLocation,
   highestBuiltinLanguageId,
   getAllGrammars
 };

src/utils.js

@@ -1,11 +1,16 @@
 // @ts-check
 const fs = require('fs');
 const util = require('util');
+const zlib = require('zlib');
 const path = require('path');
 const JSON5 = require('json5');
 const plist = require('plist');
 const uniq = require('lodash.uniq');
 
+const readFile = util.promisify(fs.readFile);
+const exists = util.promisify(fs.exists);
+const gunzip = util.promisify(zlib.gunzip);
+
 /**
  * Splits a Visual Studio Marketplace extension identifier into publisher and extension name.
  * @param {string} identifier The unique identifier of a VS Code Marketplace extension in the format 'publisher.extension-name'.
@@ -70,12 +75,14 @@ function sanitizeForClassName(str) {
     .toLowerCase();
 }
 
-const readFile = util.promisify(fs.readFile);
 const requireJson = /** @param {string} pathName */ pathName => JSON5.parse(fs.readFileSync(pathName, 'utf8'));
 const requirePlistOrJson = /** @param {string} pathName */ async pathName =>
   path.extname(pathName) === '.json' ? requireJson(pathName) : plist.parse(await readFile(pathName, 'utf8'));
 
 module.exports = {
+  readFile,
+  exists,
+  gunzip,
   parseExtensionIdentifier,
   getExtensionPath,
   getExtensionBasePath,