Mapping file parse errors are not logged to the console

[mikekberg]

Is your feature request related to a problem? Please describe.
When there is an issue loading a mapping file Wiremock.net only logs a Static MappingFile : '/app/__admin/mappings/test.json' could not be read. This file will be skipped.. This doesn't help understand why this is the cause or what is wrong with the syntax of the mapping file

Describe the solution you'd like
Detailed information about why the mapping file could not be loaded

[StefH]

#1202