Created attachment 148459 [details]
epub error without backend

SUMMARY
***
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***
this is a simple enough bug. i have stock kde neon and apparently my okular did not come with epub backend support. i did not know that.
when i tried to open an epub file, it thows an error.
i checked online and found i had to install epub backend. instead of doing apt-get, i tried discover and found the package which did run my file perfectly.

the problem is, okular did not open discover for me to tell me "this package needs to be installed to run this file. do you want to proceed?"  or why didnt it do this in the backend?

if it does not want to do in the backend, at least inform me that i should check the backend with so and so name in the package manager because that is where the package "should be".

STEPS TO REPRODUCE
1.  open epub file in okular
2.  no support for epub
3.  find okular-epub in discover
4. install package
5. run epub file

OBSERVED RESULT

the software should either try to search for the missing package itself in the package manager and install it or at least inform the user that a package with "okular-epub" name should be in the package manager that needs to be installed.

the current message that says "cannot find a plugin..." tells me okular will refuse to open this file with no recourse
EXPECTED RESULT


SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.24
KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.93.0
Qt Version: 5.15.3
Kernel Version: 5.13.0-40-generic (64-bit)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i7-4600U CPU @ 2.10GHz
Memory: 7.7 GiB of RAM
Graphics Processor: Mesa DRI Intel® HD Graphics 4400