I'm trying to run the JSBridge callback example from a 4.5 image.   JSBridge.st is loaded and I'm running under Chrome on Windows.   I get an error: "Error:primReturnFromCallback: failed.  " Digging a little in the debugger, I find in JSObjectProxy>>handleCallback, result is : "Error: Error: This block accepts 2 arguments, but was called with 0 arguments". 

Modifying the example with a callback block with 0 arguments works.

The JSBridge demo on the SqueakJS site seems to be working fine.

Any ideas?