Error when executing RPC call `delegator::get()`

[cmichi]

After having deployed our delegator example I'm unable to execute the RPC transaction get() : i32:

The return value should be i32, but it's the unit type (). There is no network traffic visible in the browsers web dev tools, hence I assume it's an error which happens already in the UI.

How to reproduce

I've attached all necessary files here.

• First deploy adder, accumulator and subber
• Then deploy delegator (with endowment 1000000) while providing the hashes of those sub-contracts:
  • accumulator_hash: 0x694f690cebfca6ada3e548747b9e9438f4a277c77e8dc66bbdbfc441d921b3c7
  • adder_hash: 0x74de7cebd87ffc53621987d0ec18f610867dfd22b56ee8f7162e3a7bbef99bd4
  • subber_hash: 0x27b8eebfe9e80ae0d90f7f7b60f4acfe530b7f1025e5b462e49719757a88f0d4

[achimcc]

• First, canvas-ui failed to display meaningful error messages, this was implmented by Display meaningfull error messages for failed contract calls #99
• The correct evaluation of the error messages revealed that the gas estimation was wrong. We traced this back to substrate in pallet-contracts: Gas estimation is too low substrate#8693
• Which was finally fixed by: contracts: Remove weight pre charging substrate#8976, which closes the issue.