Always revert state upon encountering Result::Err

[Robbepop]

This fixes some misconception between ink! and SEAL.

Brought up by @xgreenx in this comment first: #641 (comment)

[athei]

Don't you need to change the call site, too? So that the error is decoded and returned to the caller when a seal_call reverted and returned an Err?

[xgreenx]

Don't you need to change the call site, too? So that the error is decoded and returned to the caller when a seal_call reverted and returned an Err?

Yea, you are right.
@Robbepop Let me describe the issue again=) We have contract A and contract B. Contract A called some method X of contract B. Contract B reverted his call with return_value. The cotract-pallet returns CalleeReverted but fills the output buffer.
Here seal_call returns an error CalleeReverted and it is a VALID use case. Here we need to decode the output buffer and return Ok(decoded) instead of returning of CalleeReverted.

[athei]

Looks good. Now the errors should be properly forwarded to the caller.

[codecov-commenter]

Codecov Report

Merging #975 (5de41d6) into master (764a44a) will increase coverage by 0.81%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #975      +/-   ##
==========================================
+ Coverage   62.78%   63.60%   +0.81%     
==========================================
  Files         244      244              
  Lines        9148     9149       +1     
==========================================
+ Hits         5744     5819      +75     
+ Misses       3404     3330      -74     

Impacted Files	Coverage Δ
crates/lang/codegen/src/generator/dispatch.rs	0.00% <ø> (ø)
crates/lang/src/codegen/dispatch/execution.rs	0.00% <0.00%> (ø)
crates/allocator/src/bump.rs	62.50% <0.00%> (-4.17%)	⬇️
crates/env/src/api.rs	36.36% <0.00%> (+4.54%)	⬆️
crates/env/src/engine/off_chain/test_api.rs	80.85% <0.00%> (+6.38%)	⬆️
crates/env/src/engine/off_chain/impls.rs	42.98% <0.00%> (+9.64%)	⬆️
crates/env/src/engine/off_chain/db/debug_buf.rs	26.31% <0.00%> (+10.52%)	⬆️
crates/env/src/engine/off_chain/mod.rs	89.61% <0.00%> (+11.68%)	⬆️
crates/env/src/engine/off_chain/db/events.rs	100.00% <0.00%> (+12.12%)	⬆️
crates/storage/src/collections/vec/fuzz_tests.rs	100.00% <0.00%> (+15.87%)	⬆️
... and 3 more

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