Fix 'Enforce that an expression gets used' errors

Author: NikolaiProgramist

src/Parser.php

@@ -7,5 +7,11 @@
 
 function parse(string $pathToFile1, string $pathToFile2, string $format): void
 {
-    line('%s', genDiff($pathToFile1, $pathToFile2, $format));
+    $resultString = genDiff($pathToFile1, $pathToFile2, $format);
+
+    if ($resultString) {
+        line('%s', $resultString);
+    } else {
+        line('');
+    }
 }