The problem with printing the exception was that starting with
Python 3.6 the ImportError is yet another (sub) exception called
ModuleNotFoundError which can't be printed as a string and then triggers
another exception:
```
Traceback (most recent call last):
File "/home/julianoes/src/Firmware/Tools/serial/generate_config.py", line 11, in <module>
import jinja2
ModuleNotFoundError: No module named 'jinja2'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/julianoes/src/Firmware/Tools/serial/generate_config.py", line 13, in <module>
print("Failed to import jinja2: " + e)
TypeError: must be str, not ModuleNotFoundError
```
As per @bkueng's suggestion the easiest is to cast the exception to str
and that way prevent the second exception.
We now check individually for empy and genmsg.
Also, my recommendation is to use pip3 as a user to install the
dependencies as this is least intrusive and should work on all
platforms.
TSC21