Print failure info even if code_context is None

[mcbridejc]

Issue

I encountered a situation where code_context was None, which lead to a TypeError: NoneType object is not subscriptable error, which was not at all helpful in tracking down the problem. This fix allows the original error information to be printed anyway in that case.

I admit I have not dug enough into this to know if it is reasonable that code_context might sometimes be None. Possibly this is a kluge, and there is a better fix.

Background

Some background in case anyone wants to dig further:

I encountered this while working on modm PR 676. The error came while running python3 tools/scripts/docs_modm_io_generator.py -t -c -j4 -d from the 'build-docs-test' CI job. Ultimately, it was because the LogicAnalyzer module in test/modm/mock/module.lb was depending on the gpio_sampler module, which was not available for the samg55 part I added. After applying the update in this PR, I got the error below, which was much more helpful than the NoneType message :).

Error generating documentation for device samg55j19a-mu: Cannot resolve dependency ':driver:gpio_sampler' of Module(modm-test:mock:logic_analyzer)!
In file 'modm-samg/demo/ext/modm/test/modm/mock/module.lb:96' in function 'prepare':
    def prepare(self, module, options):

[salkinium]

Oh, this is fantastic!