fix: ensure prefix is set even with create_schemas_in_migrations? false

Author: zachdaniel

lib/migration_generator/phase.ex

@@ -19,12 +19,18 @@ defmodule AshPostgres.MigrationGenerator.Phase do
           Enum.map_join(operations, "\n", fn operation -> operation.__struct__.up(operation) end) <>
           "\nend"
       else
-        {pre_create, opts} =
+        pre_create =
           if schema && repo.create_schemas_in_migrations?() do
-            {"execute(\"CREATE SCHEMA IF NOT EXISTS #{schema}\")" <> "\n\n",
-             ", prefix: \"#{schema}\""}
+            "execute(\"CREATE SCHEMA IF NOT EXISTS #{schema}\")" <> "\n\n"
           else
-            {"", ""}
+            ""
+          end
+
+        opts =
+          if schema do
+            ", prefix: \"#{schema}\""
+          else
+            ""
           end
 
         pre_create <>