orm fix select item array with 1 element

application/Espo/ORM/QueryComposer/BaseQueryComposer.php

@@ -1813,9 +1813,14 @@ abstract class BaseQueryComposer implements QueryComposer
             ];
         }
 
-        if (is_array($attribute) && count($attribute) === 2) {
-            $alias = $attribute[1];
+        if (is_array($attribute) && count($attribute) === 1) {
+            $attribute = $attribute[0];
+        }
 
+        if (is_array($attribute) && count($attribute) === 2) {
+            // @todo Refactor to unite convertComplexExpression and select, noSelect, notStorable (here and below).
+
+            $alias = $attribute[1];
             $attribute0 = $attribute[0];
 
             if (!$entity->hasAttribute($attribute0)) {
@@ -1848,7 +1853,7 @@ abstract class BaseQueryComposer implements QueryComposer
         }
 
         if (!is_string($attribute)) {
-            throw new RuntimeException();
+            throw new RuntimeException("Bad select.");
         }
 
         if (!$entity->hasAttribute($attribute)) {

tests/unit/Espo/ORM/MysqlQueryComposerTest.php

@@ -3128,4 +3128,22 @@ class MysqlQueryComposerTest extends \PHPUnit\Framework\TestCase
             $this->query->composeSelect($query)
         );
     }
+
+    public function testSelections1(): void
+    {
+        $query1 = SelectBuilder::create()
+            ->select(['number'])
+            ->from('Post')
+            ->build();
+
+        $query2 = SelectBuilder::create()
+            ->select($query1->getSelect())
+            ->from('Post')
+            ->build();
+
+        $this->assertEquals(
+            $this->query->composeSelect($query1),
+            $this->query->composeSelect($query2)
+        );
+    }
 }