SNS: Internal server errors due to quotes in similar terms request

I noticed in our logs that https://sns.uba.de/umthes/de/similar.json?terms=%22naturr%C3%A4umliche triggers internal server errors while https://sns.uba.de/umthes/de/similar.json?terms=naturr%C3%A4umliche (without the leading quote) works as expected.

Is this the intended behaviour? Should we sanitize terms before sending them towards SNS and if so, what should be removed?