Update per PR review to have appropriate defaults when there are missing bits (in practice we don't allow code-gen until the blocks are non-empty, so I don't think I can test this.
Update per PR review to have appropriate defaults when there are missing bits (in practice we don't allow code-gen until the blocks are non-empty, so I don't think I can test this.

groklearning/blockly-blocks,groklearning/blockly-blocks