Crash Interpreter when arguments are wrong

[m11o]

In the wasm site, it was crashed when arguments are wrong in defined methods.

For example,

> (define sum (lambda (a b) (+ a b)))
3
> (sum 10 20)
30
> (sum 10)
RuntimeError: unreachable
    at zip-lambda-args (https://pollrobots.com/scheme/wasm/scheme.wasm:wasm-function[248]:0xbf79)
    at apply-lambda (https://pollrobots.com/scheme/wasm/scheme.wasm:wasm-function[241]:0xbd9f)
    at cont-apply-form (https://pollrobots.com/scheme/wasm/scheme.wasm:wasm-function[238]:0xbbee)
    at eval (https://pollrobots.com/scheme/wasm/scheme.wasm:wasm-function[232]:0xb7c9)
    at a.eval (https://pollrobots.com/scheme/67.d46c0a73400b858e9b00.js:1:3894)
    at a.processLine (https://pollrobots.com/scheme/67.d46c0a73400b858e9b00.js:1:8704)
    at Object.onInput (https://pollrobots.com/scheme/67.d46c0a73400b858e9b00.js:1:14287)
    at Object.onMessage (https://pollrobots.com/scheme/67.d46c0a73400b858e9b00.js:1:12005)
    at https://pollrobots.com/scheme/67.d46c0a73400b858e9b00.js:1:10930

Press <Enter> to restart scheme runtime.
stopped:

Version: v0.1-136-gb5ce0b8

We expect to display messages of errors not crashing. Thanks.