reloading breaks easyform

[scottdraves]

1. open doc/groovy/EasyFormDemos.ipynb and run the 1st cell
2. reload the page
3. run the 1st cell again

this error appears on the JS console, and the "run" button fails:

Could not open comm  --  Error: Class beaker.tag.run not found in registry 
    at utils.js:880
    at new Promise (<anonymous>)
    at Object.load_class (utils.js:865)
    at CommManager.comm_open (comm.js:84)
    at i (jquery.min.js:4)
    at Kernel._handle_iopub_message (kernel.js:1223)
    at Kernel._finish_ws_message (kernel.js:1015)
    at kernel.js:1006
    at <anonymous>
(anonymous) @ utils.js:916
Promise rejected (async)
CommManager.comm_open @ comm.js:85
i @ jquery.min.js:4
Kernel._handle_iopub_message @ kernel.js:1223
Kernel._finish_ws_message @ kernel.js:1015
(anonymous) @ kernel.js:1006
Promise resolved (async)
Kernel._handle_ws_message @ kernel.js:1006
i @ jquery.min.js:4
kernel.js:1007 Couldn't process kernel message WrappedError {stack: "Error: Could not open comm↵    at new WrappedError…9561a88cca9375b7d86bf:20123:33↵    at <anonymous>", message: "Could not open comm", error_stack: Array(2)}

[scottdraves]

classic notebook fixed, leaving open for lab fix.