mesh-doctor error message is not explicit when using invalid command line

[alexbenedicto]

When trying to use mesh-doctor, a frequent misunderstanding can be that you just need to call mesh-doctor by itself on your mesh to use it like the following:

mesh-doctor -i my_mesh.vtu

This is incorrect because you always need to specify which feature to call after your input like the following:

mesh-doctor -i my_mesh.vtu element_volumes --min 0.0

The error message when forgetting the call to the feature is not explicit at all and needs to be handled correctly, with a similar message as

mesh-doctor needs to be provided with the feature to be used amongst the current ones available : {collocated_nodes,element_volumes,...}
An example following your command could be mesh-doctor -i my_mesh.vtu element_volumes --min 0.0

The same error handling can be done with missing input file and missing keywords for the feature.