fix: preserve cached table list shape

Author: memleakd

system/Database/BaseConnection.php

@@ -1684,9 +1684,11 @@ protected function getDriverFunctionPrefix(): string
     public function listTables(bool $constrainByPrefix = false)
     {
         if (isset($this->dataCache['table_names']) && $this->dataCache['table_names']) {
-            return $constrainByPrefix
+            $tables = $constrainByPrefix
                 ? preg_grep("/^{$this->DBPrefix}/", $this->dataCache['table_names'])
                 : $this->dataCache['table_names'];
+
+            return array_values($tables);
         }
 
         $sql = $this->_listTables($constrainByPrefix);

tests/system/Database/Live/MetadataTest.php

@@ -78,7 +78,7 @@ private function dropExtraneousTable(): void
         $oldPrefix = $this->db->getPrefix();
         $this->db->setPrefix('tmp_');
 
-        Database::forge($this->DBGroup)->dropTable('widgets');
+        Database::forge($this->DBGroup)->dropTable('widgets', true);
 
         $this->db->setPrefix($oldPrefix);
     }
@@ -139,4 +139,22 @@ public function testListTablesConstrainedByExtraneousPrefixReturnsOnlyTheExtrane
             $this->dropExtraneousTable();
         }
     }
+
+    public function testListTablesReturnsListAfterCachedTableIsDropped(): void
+    {
+        try {
+            $this->createExtraneousTable();
+
+            $tables = $this->db->listTables();
+            $this->assertSame(array_values($tables), $tables);
+
+            $this->dropExtraneousTable();
+
+            $tables = $this->db->listTables();
+            $this->assertSame(array_values($tables), $tables);
+            $this->assertNotContains('tmp_widgets', $tables);
+        } finally {
+            $this->dropExtraneousTable();
+        }
+    }
 }