blocks: no warnings when connecting 'incompatible' blocks

(This one probably isn't trivial, as I think it's partially a blockly/Python limitation)

One of the things that blocks is quite good at is avoid syntax errors.

However, our current implementation doesn't protect the user from type error as well as it could.

For example, the following code fails as soon as it is run on the micro:bit

PXT gives slightly more useful feedback:

Do we have a way of giving more immediate feedback to users about type mismatches? Or even better, perhaps (although it's spooky action at a distance) automatically inserting the required conversion so it 'just works'?

A issue não menciona arquivos, testes ou pontos de entrada. Comece reproduzindo no navegador e no micro:bit o exemplo de blocos incompatíveis e, em seguida, investigue o comportamento atual do tratamento de tipos no Blockly/Python. O trabalho estará concluído quando houver uma abordagem acordada que forneça feedback imediato sobre incompatibilidade de tipos ou insira conversões seguras.

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