Fix CI-scripts for JavaScript components.

The CI-scripts assumed `python` is available on the path, but this is not necessarily the case for the JavaScript components.

ci/base.sh

@@ -19,4 +19,7 @@ script_dir() {
 }
 
 # For Windows compatibility; prevent path from ending with a ':'
-export PYTHONPATH=$(python -c 'import sys;print(":".join(sys.argv[1:]))' src $PYTHONPATH)
+if command -v python &> /dev/null
+then
+    export PYTHONPATH=$(python -c 'import sys;print(":".join(sys.argv[1:]))' src $PYTHONPATH)
+fi

ci/quality-base.sh

@@ -2,18 +2,22 @@
 
 source pipx-base.sh
 
-PYTHON_FILES_AND_FOLDERS=$(python $(script_dir)/python_files_and_folders.py)
+python_files_and_folders() {
+    echo $(python $(script_dir)/python_files_and_folders.py)
+}
 
 run_ruff() {
+    PYTHON_FILES_AND_FOLDERS=$(python_files_and_folders)
     run_pipx ruff check $PYTHON_FILES_AND_FOLDERS
     run_pipx ruff format --check $PYTHON_FILES_AND_FOLDERS
 }
 
 run_fixit() {
-    run_pipx fixit lint $PYTHON_FILES_AND_FOLDERS
+    run_pipx fixit lint $(python_files_and_folders)
 }
 
 run_mypy() {
+    PYTHON_FILES_AND_FOLDERS=$(python_files_and_folders)
     # Run mypy with or without pydantic plugin depending on whether pydantic is listed as dependency in the tools
     # section of the optional dependencies in the pyproject.toml file.
     pydantic_spec=$(spec pydantic)
@@ -32,15 +36,15 @@ run_pyproject_fmt() {
 }
 
 run_bandit() {
-    run_pipx bandit --configfile pyproject.toml --quiet --recursive $PYTHON_FILES_AND_FOLDERS
+    run_pipx bandit --configfile pyproject.toml --quiet --recursive $(python_files_and_folders)
 }
 
 run_pip_audit() {
     run_pipx pip-audit --strict --progress-spinner=off $(python $(script_dir)/requirements_files.py "-r %s")
 }
 
 run_vulture() {
-    run_pipx vulture --min-confidence 0 $PYTHON_FILES_AND_FOLDERS .vulture_ignore_list.py $@
+    run_pipx vulture --min-confidence 0 $(python_files_and_folders) .vulture_ignore_list.py $@
 }
 
 run_vale() {