PHP8.1 fixes

[asivery]

Fixed #3900 and #3890 among other warnings.

[asivery]

@splitbrain Hello, I've fixed the problems you've mentioned, and I've also found a bug (at least I presume it's a bug - I didn't get any warnings / errors after applying 170f205), where the whole image would get re-read after reading any tag. Please let me know if you'd like me to change anything else.

[splitbrain]

Nice work. I changed the exception handling slightly in d40e7d0

Since you seem to be somewhat familiar with the JpegMeta code by now and have started fixing bugs, I see two options if you would want to dig deeper:

1. if you're interested in maintaining your own Open Source project, extracting the the JpegMeta class into its own composer project might be interesting. It would need a lot of clean up, adding unit tests and maybe refactoring it into multiple classes.
2. we are thinking of replacing this class completely, by a better maintained project (see Make 3rd party libs composer dependencies #1970). https://github.com/pel/pel seems to be the most likely candidate. a DokuWiki PR replacing the use of JpegMeta with a composer dependency like PEL would be very welcome.

Just a suggestion in case you want to dig a little deeper.

[asivery]

Thanks a lot! I might look into it, though not sure which way would be the best to go. The way I see it is, PEL would probably be better for Exif-only, but the current JpegMeta implementation supports not only Exif metadata, but also Adobe and some others, so by going with PEL we'd lose some functionality in favor of more stable code. I'll think about it, and might do a PR with one of the solutions you've listed above later.