Manage errors at decoding

[Arwalk]

There is currently no check on the validity of the values (as in, varint decoded is bigger than actually possible to fit in the struct)

Need to do this for any kind of varint.

Impact on decode_varint (if it doesnt fit, return error) and on the transformation done to fit the final structure in pb_decode

[Arwalk]

Wiredecoder should check for the fully encoded tag, which would eliminate errors in wirevalues naturally.

[Arwalk]

Wiredecoder should check for the fully encoded tag, which would eliminate errors in wirevalues naturally.

Done indirectly with acb2a57c1612a3fb096efc383ac1b3ffa8548d93