HAving stumbled on this issue as I was looking for some other troubles woth the modules, I noticed the following:
# About to run '/etc/munin/plugins/mxruntime_somecust'
/home/xxx/application/data/config/m2ee.yaml: line 59: mxnode:: command not found
/home/xxx/application/data/config/m2ee.yaml: line 62: mxjar_repo:: command not found
The above is telling me that somehow you are trying to execute or source the
/home/xxx/application/data/config/m2ee.yaml
file, instead of reading it as a configuration file!