Improve Weaviate error handling

[vga91]

If we create a collection 'TestCollection' e.g. with size 4

CALL apoc.vectordb.weaviate.query($host, 'TestCollection', [0.2, 0.1, 0.9], null, 5, $conf)

And we execute a weaviate query with an embedding with size e.g. 3, so that it doesn't match the one specified with the schema collection,
it will returned an unclear error size:

CALL apoc.vectordb.weaviate.query($host, 'TestCollection', [0.2, 0.1, 0.9], null, 5, $conf)

The result is:

java.lang.NullPointerException: Cannot invoke "java.util.List.stream()" because "collectionValue" is null

Instead, it should return the error cause.