Fix ParamName in guard of Base64.GetMaxEncodedToUtf8Length

[lilinus]

Without fix ParamName of the exception was (uint)bytesLength

Also fix same issue for Base64Url.GetEncodedLength

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[github-actions]

Holistic Review

Motivation: Base64.GetEncodedLength (surfaced through GetMaxEncodedToUtf8Length) and Base64Url.GetEncodedLength validate their input with ArgumentOutOfRangeException.ThrowIfGreaterThan<uint>((uint)bytesLength, MaximumEncodeLength). Because that overload derives paramName from CallerArgumentExpression, the thrown exception's ParamName was the literal expression "(uint)bytesLength" rather than the public parameter name bytesLength. That is confusing to callers and inconsistent with the non-NET fallback path, which already threw with nameof(bytesLength).

Approach: The fix passes nameof(bytesLength) explicitly to ThrowIfGreaterThan in both the Base64 and Base64Url encoders, so ParamName is now the correct bytesLength. The tests in Base64EncoderUnitTests and Base64UrlEncoderUnitTests are updated to assert the expected ParamName (Assert.Throws<ArgumentOutOfRangeException>("bytesLength", ...)) for both the overflow and negative-input cases, locking in the corrected behavior.

Summary: This is a minimal, correct, and well-targeted bug fix. The change aligns the #if NET validation path with the existing non-NET fallback (throw new ArgumentOutOfRangeException(nameof(bytesLength))), so both paths now report the same ParamName. The updated assertions provide regression coverage. The ParamName value is a technically observable change, but moving from an internal expression string to the documented parameter name is a strict improvement and not a meaningful compatibility concern. No functional behavior, thrown exception type, or valid-input results change. I found no correctness, performance, or convention issues. LGTM.

Note

This review was generated by this repository's Holistic Review agentic workflow to complement the built-in Copilot review.

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[MihaZupan]

Looks like Base64.GetMaxEncodedToUtf8Length's parameter is called just length

[lilinus]

I missed that detail