refs matomo-org#5144 better fix for array to string to conversion.

Noticed this hack while I worked on the tracker refactoring. Dispatch
should always return a string. Fixing the problem where it actually occurs.
An even better fix would be not to support serialize=0 for format PHP as
it is meant only for internal requests. If someone wants to access data
serialize=1 should be set.

core/dispatch.php

@@ -35,9 +35,7 @@
         $controller->init();
         $response = $controller->dispatch();
 
-        if (is_array($response)) {
-            var_export($response);
-        } elseif (!is_null($response)) {
+        if (!is_null($response)) {
             echo $response;
         }
     } catch (Exception $ex) {

plugins/API/Controller.php

@@ -30,7 +30,13 @@ function index()
         }
 
         $request = new Request('token_auth=' . Common::getRequestVar('token_auth', 'anonymous', 'string'));
-        return $request->process();
+        $response = $request->process();
+
+        if (is_array($response)) {
+            $response = var_export($response, true);
+        }
+
+        return $response;
     }
 
     public function listAllMethods()