Some Fixes PlainOpcodes.s.sol

[lordofdegen]

Time spent on this PR: 0.5 days

Pull request type: Bugfix

What is the current behavior?

Resolves #1: Handling deployerPrivateKey might throw an error if it's set to 0
If the deployerPrivateKey is null, it could lead to improper handling or unexpected behavior when calling vm.startBroadcast.

Resolves #2: Missing success checks for contract calls
There are no success checks for the Counter and PlainOpcodes contract calls. If the contract deployment fails, it won't be explicitly logged.

Resolves #3: Type issue in the create function
The create function is called with type(Counter).creationCode, which returns the contract bytecode. However, it's unclear if the expected argument for create matches this return value. In the PlainOpcodes contract, create might expect different data types (e.g., hashes or precompiled codes)."

What is the new behavior?

• Now there's a null check in place.
• Contract deployments now have success checks.
• We can now confirm that create expects bytecode, and the passed value is correct. If an address or hash is needed, adjust the parameter.

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This change is 

[enitrat]

Hi, I don't think there are any issues with this file