Made Theme::basePath optional fixes #2810

framework/base/Theme.php

@@ -82,12 +82,11 @@ class Theme extends Component
     {
         parent::init();
 
-        if (($basePath = $this->getBasePath()) !== null) {
-            if (empty($this->pathMap)) {
-                $this->pathMap = [Yii::$app->getBasePath() => [$basePath]];
+        if (empty($this->pathMap)) {
+            if (($basePath = $this->getBasePath()) == null) {
+                throw new InvalidConfigException('The "basePath" property must be set.');
             }
-        } else {
-            throw new InvalidConfigException('The "basePath" property must be set.');
+            $this->pathMap = [Yii::$app->getBasePath() => [$basePath]];
         }
     }
 
@@ -172,14 +171,4 @@ class Theme extends Component
             throw new InvalidConfigException('The "baseUrl" property must be set.');
         }
     }
-
-    /**
-     * Converts a relative file path into an absolute one using [[basePath]].
-     * @param  string $path the relative file path to be converted.
-     * @return string the absolute file path
-     */
-    public function getPath($path)
-    {
-        return $this->getBasePath() . DIRECTORY_SEPARATOR . ltrim($path, '/\\');
-    }
 }