[BUGFIX] Choose between global/local variable based on primary identi…

…fier

With the previous implementation of ScopedVariableProvider,
variables that contained arrays or object structures could behave
incorrectly in a scoped context. When accessing a object path
in a fluid template (e. g. myVar.subKey), the value of that
"sub variable" was considered for the decision which variable
(global or local) should be used.

This behavior is incorrect, only the "primary" variable name
should determine if a local variable is set or not (and should
fall back to a global variable). This would mean that a non-existing
sub value in a local variable would trigger a fallback to the
global variable.

This change restores the correct behavior: Only the "primary"
variable name is checked initially. If the variable exists in the
local variables, those will be used, even if the requested sub value
doesn't exist there. Only if the "primary" variable name doesn't
exist in local variables, global variables will be used instead.

Resolves #848

src/Core/Variables/ScopedVariableProvider.php

@@ -96,7 +96,10 @@ public function get($identifier): mixed
     public function getByPath($path): mixed
     {
         $path = $this->resolveSubVariableReferences($path);
-        return $this->localVariables->getByPath($path) ?? $this->globalVariables->getByPath($path);
+        $identifier = explode('.', $path, 2)[0];
+        return $this->localVariables->exists($identifier)
+            ? $this->localVariables->getByPath($path)
+            : $this->globalVariables->getByPath($path);
     }
 
     public function getAllIdentifiers(): array

tests/Unit/Core/Variables/ScopedVariableProviderTest.php

@@ -176,6 +176,13 @@ public static function getVariableByPathDataProvider(): \Generator
             'local',
         ];
 
+        yield 'local undefined subkey overrides global set subkey' => [
+            ['myVar' => ['myKey' => 'global']],
+            ['myVar' => ['myKey' => null]],
+            'myVar.myKey',
+            null,
+        ];
+
         yield 'variable variables using only globals' => [
             ['myVar' => ['sub' => 'global'], 'path' => 'sub'],
             [],