Use unstable Json API with guarantee;

Move plugin center from ./center to ./plugin/center

backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/center/CuiPluginCenter.kt → backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/plugin/center/CuiPluginCenter.kt

@@ -9,7 +9,7 @@
 
 @file:OptIn(MiraiExperimentalAPI::class)
 
-package net.mamoe.mirai.console.center
+package net.mamoe.mirai.console.plugin.center
 
 import io.ktor.client.HttpClient
 import io.ktor.client.engine.cio.CIO
@@ -24,7 +24,9 @@ import net.mamoe.mirai.utils.MiraiExperimentalAPI
 import java.io.File
 
 @OptIn(UnstableDefault::class)
-internal val json = Json(JsonConfiguration(isLenient = true, ignoreUnknownKeys = true))
+internal val json = runCatching {
+    Json(JsonConfiguration(isLenient = true, ignoreUnknownKeys = true))
+}.getOrElse { Json(JsonConfiguration.Stable) }
 
 @OptIn(KtorExperimentalAPI::class)
 internal val Http = HttpClient(CIO)

backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/center/PluginCenter.kt → backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/plugin/center/PluginCenter.kt

@@ -7,7 +7,7 @@
  * https://github.com/mamoe/mirai/blob/master/LICENSE
  */
 
-package net.mamoe.mirai.console.center
+package net.mamoe.mirai.console.plugin.center
 
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable