Assertion failure when building index on freebase-rdf-latest.nt

[niklas88]

When trying to build the index with a debug build the following assertion is violated
https://github.com/Buchhold/QLever/blob/master/src/util/Conversions.h#L75
This could be a problem with my dataset but we may also need to be less strict. I'll investigate.

[niklas88]

So it seems this always gets called after testing for a value literal with isXsdValue() which doesn't check for the closing '>' so my firs preliminary guess is that we should either check for the '>' in isXsdValue() as well so as to make it required for value literals or we should not assert for it.

In the freebase-rdf-latest a quick grep found at least violations of the following form

<http://rdf.freebase.com/ns/m.0n34wnj>  <http://www.w3.org/2000/01/rdf-schema#label>    "Peace(^^)v"@ja .
...
<http://rdf.freebase.com/ns/m.0g7bd6q>  <http://www.w3.org/2000/01/rdf-schema#label>    "^^^"@en        .

also some weird stuff that looks like JavaScript in a literal string. The following egrep was used

egrep --color --text -e '\^\^[^[:space:]]+[^>][[:space:]]+' freebase-rdf-latest

[niklas88]

This was fixed in d99c50d when support for 123^^xsd:integer was added.