do not crash if autocmake.yml does not contain any modules

update.py

@@ -57,6 +57,7 @@ def fetch_modules(config, relative_path, download_directory):
                        total=num_sources,
                        width=30)
 
+    if 'modules' in config:
         i = 0
         for t in config['modules']:
             for k, v in t.items():
@@ -106,7 +107,6 @@ def fetch_modules(config, relative_path, download_directory):
                                            done=i,
                                            total=num_sources,
                                            width=30)
-
         print('')
 
     return modules, cleaned_config