@csomh . Review please :)

Is this connected with some known od opened bug/ticket?
Do you have some specific build id, where it happens? I found multiple builds in mbs, where even module_build['tasks'] was empty, so "rpms" item access would raise an exception. But maybe it is unrelated.

These outer-parenthesis can be dropped, so this can be:

for pkg_name, task_info in module_build['tasks'].get("rpms", {}).items():

Is this connected with some known od opened bug/ticket?
Do you have some specific build id, where it happens? I found multiple builds in mbs, where even module_build['tasks'] was empty, so "rpms" item access would raise an exception. But maybe it is unrelated.

No, it doesn't connect with some opened bug or ticket. I've discovered it in the process of integration tests implementation. There will be no "rpms" key in "tasks" when a module without any components is built. And that in such cases watching the module build will fail. You can try build_id=1583

Or in Fedora MBS:

$ fedpkg module-build-watch 7216
Could not execute module_build_watch: 'rpms'

Right, that fixes the issue.
There is another occurence of the construction, that might involve the functionality:
line 3941: task_infos = module_build['tasks']['rpms']
What do you think?

with the fix in the code:
module-build-watch 7216
Could not execute module_build_watch: float division by zero

The "division by zero" error comes from stats_module_build_components. When there are no components built, the iteration there will never execute, so stats['total'] will be zero.

To fix that stats['completion_percentage'] should be initialised with 100 instead of 0, and calculating its value should only happen when stats['total'] > 0 after the for-loop.

module_build['tasks']['rpms'] in line 3941 is a different data structure then the one produced by the MBS API, in that case 'rpms' will always be set, even though it might be empty.

Commit 02affb45 fixes this pull-request

Thanks to you both, I modified the original commit that way.