more graceful error message for missing codecs

[tpltnt]

When codes are missing (i.e. install_codecs.sh was not run during install), there should be an error message hinting at the missing codecs and not just a floating point exception (as it is the case currently). This ticket spawned of #3855. The codec installation is a separate step due to patent/licensing issue in some jurisdictions. This is only hinted at in the installation guide.

[bakercp]

Just ran into this today. Definitely need this. Even just updating the RPI install guide, for instance, to mention the possible outcomes of installing or not installing codecs could help.