[Feature] Better log messages for failed web scrapping

[math-GH]

If the web scrapping fails it writes an error log message.

But it does not help very much because the message has not useful information

I wished that here are more hints/information what could be wrong f.e. is there an issue with entering the website? is there an issue with finding the items? etc.

[math-GH]

Is it a problem that the <doctype> is not in the first line of HTML?

(github.com website)

[Frenzie]

It shouldn't be.

[Alkarex]

Is it a problem that the <doctype> is not in the first line of HTML?

We are trimming leading white-space (while preserving BOM) to avoid such problems

FreshRSS/lib/lib_rss.php

Line 578 in f958eae

$body = trim($body, " \n\r\t\v"); // Do not trim \x00 to avoid breaking a BOM