In case a user accidentally uses a wrong JSON file (e.g. naming.json,
which is the config file for namingng.py), the code could give a
confusing exception. This happens when the key 'script' is not defined
as a string.
This is solved by testing the key for existence and type. In case
'script' is not a key or refers to a type other than a string, a clear
error is given, stating for example: 'Loading naming.json failed. script
must be set to a string value.'
The message is kept in line with other messages. Maybe it can be
clarified further, e.g. 'Loading naming.json failed. A key "script" must
be set with a string value referring to a Python script.' - in which
case the errors relating to other keys may also be clarified.
Currently the `AddonInfo` is generated and discarded on each addon
invocation. This leads to an unnecessary process invocation for each
addon on each file.
Also if an addon is completely broken we will still perform the whole
analysis only for it to be failed at the end so we should bail out early
if we know it doesn't work at all.
thingsconnected
Oliver Stöneberg