Fix parse error when using length with @root

zordius/lightncandy#370

Author: theodorejb

src/Compiler.php

@@ -199,11 +199,11 @@ protected static function getVariableName(Context $context, array $var, ?array $
             if ($levels > 0) {
                 $checks[] = "isset($base)";
             }
+            $p = count($var) ? Expression::arrayString($var) : '';
+            if ($p !== '' && ($spvar || $levels === 0)) {
+                $checks[] = "isset($base$p)";
+            }
             if (!$spvar) {
-                $p = count($var) ? Expression::arrayString($var) : '';
-                if ($levels === 0 && $p !== '') {
-                    $checks[] = "isset($base$p)";
-                }
                 $checks[] = ("$base$p" == '$in') ? '$inary' : "is_array($base$p)";
             }
             $lenStart = '(' . ((count($checks) > 1) ? '(' : '') . implode(' && ', $checks) . ((count($checks) > 1) ? ')' : '') . " ? count($base" . Expression::arrayString($var) . ') : ';

tests/RegressionTest.php

@@ -1383,6 +1383,13 @@ public static function issueProvider(): array
                 'expected' => '<p class="empty">bar</p>',
             ],
 
+            [
+                'id' => 370,
+                'template' => '{{@root.items.length}}',
+                'data' => ['items' => [1, 2, 3]],
+                'expected' => '3',
+            ],
+
             [
                 'template' => '{{#each . as |v k|}}#{{k}}{{/each}}',
                 'data' => ['a' => [], 'c' => []],