Fix premature returns for argument/pointer checks in SOSDacImpl.cs

[Copilot]

Description

Argument and pointer validation checks at the start of SOSDacImpl methods were returning early (before the try/catch), bypassing the catch block's HResult conversion and the #if DEBUG legacy comparison block.

Changes

• E_INVALIDARG checks → moved inside try, replaced return HResults.E_INVALIDARG with throw new ArgumentException()
• E_POINTER checks → moved inside try, replaced return HResults.E_POINTER with throw new NullReferenceException()
• if/else guard patterns (ISOSDacInterface14 methods, GetILForModule, GetMethodDescFromToken, TraverseModuleMap) → flattened into unified try/catch with throws
• Switch default: cases (GetMethodDescFromToken, TraverseModuleMap) → replaced hr = HResults.E_INVALIDARG with throw new ArgumentException() so execution halts rather than falling through
• GetPEFileName → inner return HResults.E_NOTIMPL inside try replaced with throw new NotImplementedException() to prevent CopyStringToBuffer from running on empty paths
• SOSMethodEnum.GetCount → added try/catch wrapper; return HResults.E_POINTER → throw new NullReferenceException()
• GetThreadFromThinlockID → fixed latent bug: null check was setting hr but not preventing the try block from running, causing *pThread dereference on a null pointer

Before / After pattern:

// Before — bypasses catch and #if DEBUG block
int ISOSDacInterface.GetThreadData(ClrDataAddress thread, DacpThreadData* data)
{
    if (thread == 0 || data == null)
        return HResults.E_INVALIDARG;   // skips try/catch and DEBUG comparison

    int hr = HResults.S_OK;
    try { ... }
    catch (Exception ex) { hr = ex.HResult; }
    ...
}

// After — check participates in unified error handling
int ISOSDacInterface.GetThreadData(ClrDataAddress thread, DacpThreadData* data)
{
    int hr = HResults.S_OK;
    try
    {
        if (thread == 0 || data == null)
            throw new ArgumentException();
        ...
    }
    catch (Exception ex) { hr = ex.HResult; }
    ...
}

Testing

• All 832 existing cDAC unit tests pass.

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[max-charlamb]

lgtm, nice cleanup.

Especially good find on the bug in GetThreadFromThinlockID

[Copilot]

Pull request overview

This pull request refactors error handling in SOSDacImpl.cs by moving argument and pointer validation checks from before try blocks to inside try blocks, converting early returns to thrown exceptions. The goal is to ensure that the catch block can handle HResult conversion and that DEBUG comparison blocks work correctly.

Changes:

• Moved null pointer and invalid argument checks from before try blocks to inside try blocks across approximately 30 methods
• Changed early return HResults.E_INVALIDARG statements to throw new ArgumentException() inside try blocks
• Changed early return HResults.E_POINTER statements to throw new NullReferenceException() inside try blocks
• Restructured methods like GetILForModule, GetMethodDescFromToken, and TraverseModuleMap from if/else structures to unified try/catch blocks
• Added try/catch wrapper to SOSMethodEnum.GetCount