Check if file exists (#1246)

server/src/main/kotlin/suwayomi/tachidesk/graphql/server/TemporaryFileStorage.kt

@@ -11,6 +11,7 @@ import kotlin.concurrent.thread
 import kotlin.io.path.ExperimentalPathApi
 import kotlin.io.path.deleteIfExists
 import kotlin.io.path.deleteRecursively
+import kotlin.io.path.exists
 import kotlin.io.path.name
 import kotlin.io.path.outputStream
 import kotlin.time.Duration.Companion.days
@@ -46,7 +47,7 @@ object TemporaryFileStorage {
 
     fun retrieveFile(name: String): Path {
         val file = folder.resolve(name).normalize()
-        check(file.startsWith(folder)) {
+        check(file.startsWith(folder) && file.exists()) {
             "File $name is not in ${folder.name}"
         }
         return file