Fix remaining psalm errors

Author: villfa

src/FakePdoStatementTrait.php

@@ -393,7 +393,7 @@ public function fetch(
      */
     public function fetchColumn($column = 0)
     {
-        /** @var array|false $row */
+        /** @var array<int, scalar>|false $row */
         $row = $this->fetch(\PDO::FETCH_NUM);
         if ($row === false) {
             return $row;

src/Processor/Expression/FunctionEvaluator.php

@@ -587,7 +587,7 @@ private static function sqlSubstringIndex(
         $delim = (string) Evaluator::evaluate($conn, $scope, $delimiter, $row, $result);
         $pos = $args[2];
 
-        if ($pos !== null) {
+        if ($pos !== null && $delim !== '') {
             $count = (int) Evaluator::evaluate($conn, $scope, $pos, $row, $result);
             $parts = \explode($delim, $string);
 

src/Schema/TableDefinition.php

@@ -29,7 +29,7 @@ class TableDefinition
     public $columns;
 
     /**
-     * @var array
+     * @var array<string>
      */
     public $primaryKeyColumns;
 
@@ -46,6 +46,7 @@ class TableDefinition
     /**
      * @param array<string, Column> $columns
      * @param array<string, Index> $indexes
+     * @param array<string> $primaryKeyColumns
      */
     public function __construct(
         string $name,