proxyspace assignment triggers empty error

[htor]

if you evaluate this code with sclang.interpret() i (correctly) get an error:

(
ProxySpace.push(s);
~a = "b";
)

but the error does not contain anything useful:

SCLangError { data: {}, type: 'Error', error: {} }

i would expect the error field to contain info about the actual error (taken from sc-ide):

ERROR: 'prepareForProxySynthDef' should have been implemented by Char.
RECEIVER:
   Character 98 'b'
...

debug output from sclang when i turn debug: true on:

debug   SuperColliderJS.interpret("ck3dd1svv0000y6rvgr6hlj48","(__NL__ProxySpace.push(s);__NL__~a = \"b\";__NL__)",nil,true,false,false);
logger.js:114 debug   
SUPERCOLLIDERJS:ck3dd1svv0000y6rvgr6hlj48:CAPTURE:START


SUPERCOLLIDERJS:ck3dd1svv0000y6rvgr6hlj48:CAPTURE:END

SUPERCOLLIDERJS:ck3dd1svv0000y6rvgr6hlj48:START:Error
SUPERCOLLIDERJS:ck3dd1svv0000y6rvgr6hlj48:CHUNK:{}
SUPERCOLLIDERJS:ck3dd1svv0000y6rvgr6hlj48:END:Error
SUPERCOLLIDERJS.interpreted
->