fix: set field file_type not required

xposed/src/main/java/moe/fuqiuluo/shamrock/remote/action/handlers/GetFile.kt

@@ -9,13 +9,14 @@ import moe.fuqiuluo.shamrock.utils.FileUtils
 import moe.fuqiuluo.symbols.OneBotHandler
 import java.util.Base64
 
-@OneBotHandler("get_file") internal object GetFile : IActionHandler() {
+@OneBotHandler("get_file") 
+internal object GetFile : IActionHandler() {
     override suspend fun internalHandle(session: ActionSession): String {
         val file = session.getString("file")
             .replace(regex = "[{}\\-]".toRegex(), replacement = "")
             .replace(" ", "")
             .split(".")[0].lowercase()
-        val fileType = session.getString("file_type")
+        val fileType = session.getStringOrNull("file_type") ?: "base64"
         return invoke(file, fileType, session.echo)
     }
 
@@ -23,7 +24,7 @@ import java.util.Base64
         val targetFile = FileUtils.getFileByMd5(file)
         return if (targetFile.exists()) {
             when (fileType) {
-                "base64" -> ok(
+                "base64", "" -> ok(
                     OutResourceByBase64(
                         "/res/${targetFile.nameWithoutExtension}",
                         Base64.getEncoder()
@@ -40,5 +41,5 @@ import java.util.Base64
         }
     }
 
-    override val requiredParams: Array<String> = arrayOf("file", "file_type")
-}
+    override val requiredParams: Array<String> = arrayOf("file")
+}