refactor: deprecate redundant non-null on user agent

[yhkee0404]

Extends #73 that fixes #70 where getStringValue would have thrown NullPointerException because its return type String did not allow null which config.getString(key) could indeed return.

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/Moder.kt

Lines 141 to 150 in 4575859

	private fun getStringValue(key: String): String {
	val subscriptionId = this.subscriptionId
	if (subscriptionId < 0) {
	return ""
	}
	val iCclInstance = this.loadCachedInterface { carrierConfigLoader }
	val config = iCclInstance.getConfigForSubId(subscriptionId, iCclInstance.defaultCarrierServicePackageName)
	return config.getString(key)
	}

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/Moder.kt

Lines 222 to 223 in 4575859

	val userAgentConfig: String
	get() = this.getStringValue(KEY_IMS_USER_AGENT)

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/pages/Config.kt

Line 60 in 4575859

configuredUserAgent = moder.userAgentConfig

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/pages/Config.kt

Line 47 in 4575859

var configuredUserAgent by rememberSaveable { mutableStateOf("") }

That is why this null check has been added since #73:

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/pages/Config.kt

Lines 60 to 64 in 622def3

	configuredUserAgent = try {
	moder.userAgentConfig
	} catch (e: java.lang.NullPointerException) {
	null
	}

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/pages/Config.kt

Line 47 in 622def3

var configuredUserAgent: String? by rememberSaveable { mutableStateOf("") }

However, it has become deprecated since #387 because getStringValue has started to prevent the exception by returning String? instead of just String with its null return being typecast into an empty string.

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/Moder.kt

Line 271 in 240d0b2

fun getStringValue(key: String): String? {

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/Moder.kt

Lines 456 to 457 in 240d0b2

	val userAgentConfig: String
	get() = this.getStringValue(KEY_IMS_USER_AGENT) ?: ""

In fact, we do not even need the typecast as well if we also make userAgentConfig nullable as it has been allowed since #73.

pixel-volte-patch/app/src/main/java/dev/bluehouse/enablevolte/pages/Config.kt

Line 77 in 240d0b2

var configuredUserAgent: String? by rememberSaveable { mutableStateOf("") }

You can download and test the built apk here but need to uninstall the previous release if any: https://github.com/yhkee0404/pixel-volte-patch/releases/tag/1.3.1_PR_426_430_431_432