`qt install:demo` skips adding `Api` module config when `modules.php` already contains an existing module

[armanist]

Description

When installing the demo modules using the CLI command:

php qt install:demo

the command correctly generates Web and Api module files and related configs if modules.php is empty or only contains demo modules.

However, if modules.php already contains any existing module before running the command, the behavior becomes inconsistent.

Expected Behavior

If modules.php already contains one or more modules, running:

php qt install:demo

should append both Web and Api modules to the configuration, without skipping any sections.

Actual Behavior

Module files for Web and Api are generated correctly

• modules.php is updated only with the Web module
• The Api module configuration is silently skipped