Do not load config from empty cache file

This change solves a fatal error that I've been encountering, whenever
the cache file is present, but empty:

Uncaught TypeError: Cannot assign int to property
Laminas\ConfigAggregator\ConfigAggregator::$config of type array

So, this change returns false if the config file is present but empty.

Signed-off-by: Matthew Setter <matthew@matthewsetter.com>

Author: settermjd

src/ConfigAggregator.php

@@ -257,6 +257,10 @@ private function loadConfigFromCache(null|string $cachedConfigFile): bool
             return false;
         }
 
+        if (filesize($cachedConfigFile) === 0) {
+            return false;
+        }
+
         $this->config = require $cachedConfigFile;
         return true;
     }

test/ConfigAggregatorTest.php

@@ -230,6 +230,14 @@ public function testConfigAggregatorSetsHandlesUnwritableCache(): void
         self::assertFileDoesNotExist($this->cacheFile);
     }
 
+    public function testConfigAggregatorDoesNotLoadConfigFromCacheIfCacheFileIsEmpty(): void
+    {
+        file_put_contents($this->cacheFile, '');
+        $aggregator = new ConfigAggregator([], $this->cacheFile);
+
+        self::assertEmpty($aggregator->getMergedConfig());
+    }
+
     public function testConfigAggregatorCanLoadConfigFromCache(): void
     {
         $expected = [