getStorageAt from empty cell now returns 0x0 instead of null

[ajlopez]

Description

JSON RPC method eth_getStorageAt now returns 0x0 instead of null if the storage cell to be retrieved is empty (the default value is then zero)

Motivation and Context

Returning null riases some issues with the ecosystem, ie geth console and other integration tools

How Has This Been Tested?

Adding code tests, and manually

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• Tests for the changes have been added (for bug fixes / features)
• Requires Activation Code (Hard Fork)

• Other information:

Please, we need more info about other getStorageAt compatibility. For example, our implementation returns 0x0000000000000000000000000000000000000000000000000000000000000001 when the storage cell contains the value ONE, but ganache returns 0x01. Is it an issue? Which is the value returned by geth and other implementations? Maybe they expect 0x1 as in other cases (with leading zeroes removed)

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

100.0% Coverage
0.0% Duplication

[fedejinich]

lgtm!