Use sourceCache if isSupported check passes, otherwise proceed without cache and do not throw an exception

- so that php-di does not break if there is any problem with apcu - instead of having to wrap ContainerBuilder::build() with try...catch block

Author: falkenhawk

src/ContainerBuilder.php

@@ -120,10 +120,8 @@ public function build()
         // Mutable definition source
         $source->setMutableDefinitionSource(new DefinitionArray([], $autowiring));
 
-        if ($this->sourceCache) {
-            if (!SourceCache::isSupported()) {
-                throw new \Exception('APCu is not enabled, PHP-DI cannot use it as a cache');
-            }
+        // use cache if isSupported check passes, otherwise proceed without cache and do not throw an exception
+        if ($this->sourceCache && SourceCache::isSupported()) {
             // Wrap the source with the cache decorator
             $source = new SourceCache($source, $this->sourceCacheNamespace);
         }