Safeguard all call class's public methods against NPE

[rahul-lohra]

Goal

Closes #AND-1350
Safeguard all call class's public methods against NPE

Implementation

Wrap all Call class's public method which returns Result with try-catch

@OptIn(ExperimentalContracts::class)
internal inline fun <T : Any> runResultCatchingCancellable(block: () -> Result<T>): Result<T> {
    contract { callsInPlace(block, InvocationKind.AT_MOST_ONCE) }
    return try {
        block()
    } catch (ce: CancellationException) {
        throw ce
    } catch (npe: NullPointerException) {
        Result.Failure(Error.ThrowableError(npe.message ?: "NullPointerException caught", npe))
    }
}

🎨 UI Changes

None

Testing

Smoke test video/audio call

[github-actions]

PR checklist ✅

All required conditions are satisfied:

• Title length is OK (or ignored by label).
• At least one pr: label exists.
• Sections ### Goal, ### Implementation, and ### Testing are filled, or the PR is bot-authored.
• An issue is linked (Linear ticket or GitHub issue), or the PR is bot-authored.

🎉 Great job! This PR is ready for review.

[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-video-android-core	12.27 MB	12.29 MB	0.02 MB	🟢
stream-video-android-ui-xml	5.68 MB	5.70 MB	0.02 MB	🟢
stream-video-android-ui-compose	6.20 MB	6.20 MB	0.00 MB	🟢