Add remaining missing return types to safe methods

Author: wouterj

Node/ConditionalNode.php

@@ -40,7 +40,7 @@ public function compile(Compiler $compiler): void
         ;
     }
 
-    public function evaluate(array $functions, array $values)
+    public function evaluate(array $functions, array $values): mixed
     {
         if ($this->nodes['expr1']->evaluate($functions, $values)) {
             return $this->nodes['expr2']->evaluate($functions, $values);

Node/FunctionNode.php

@@ -40,7 +40,7 @@ public function compile(Compiler $compiler): void
         $compiler->raw($function['compiler'](...$arguments));
     }
 
-    public function evaluate(array $functions, array $values)
+    public function evaluate(array $functions, array $values): mixed
     {
         $arguments = [$values];
         foreach ($this->nodes['arguments']->nodes as $node) {

Node/UnaryNode.php

@@ -45,7 +45,7 @@ public function compile(Compiler $compiler): void
         ;
     }
 
-    public function evaluate(array $functions, array $values)
+    public function evaluate(array $functions, array $values): mixed
     {
         $value = $this->nodes['node']->evaluate($functions, $values);