yarn/tasks/main.yml: Support skip_role_on_error flag

roles/yarn/tasks/main.yml

@@ -26,11 +26,12 @@
     var: yarn_installed
 
 
+- block:
+
   - name: Install Yarn if 'yarn_installed' not defined, e.g. in {{ iiab_state_file }}    # /etc/iiab/iiab_state.yml
     include_tasks: install.yml
     when: yarn_installed is undefined
 
-
   - name: Add 'yarn' variable values to {{ iiab_ini_file }}
     ini_file:
       path: "{{ iiab_ini_file }}"    # /etc/iiab/iiab.ini
@@ -46,3 +47,10 @@
         value: "{{ yarn_install }}"
       - option: yarn_enabled
         value: "{{ yarn_enabled }}"
+
+  rescue:
+
+  - name: 'SEE ERROR ABOVE (skip_role_on_error: {{ skip_role_on_error }})'
+    fail:
+      msg: ""
+    when: not skip_role_on_error