Bug fix: Zip operator crash and `len` warning

Fixed one crash and one extra warning message:

• Zip now won't crash when trying to do the internal type checking. It does not yet return the proper result, but that should be safe for most uses (see #150).
• len operator no longer produces a warning and type checks as a float.

What's Changed

• Type-Checking the Zip operator on Dictionary should not crash by @gordonwatts in #149
• Test that triggers the len error by @gordonwatts in #151

Full Changelog: 3.3.2...3.3.3