fix: retrieve all files when deleting oldest file

alters the filestore so that it obtains all files (including from the legacy directory) when the max
number of files is reached, and the oldest file needs to be deleted

sdk/src/main/java/com/bugsnag/android/FileStore.java

@@ -10,6 +10,7 @@
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 
@@ -56,14 +57,16 @@ String write(@NonNull T streamable) {
 
         // Limit number of saved errors to prevent disk space issues
         if (storageDir.isDirectory()) {
-            File[] files = storageDir.listFiles();
-            if (files != null && files.length >= maxStoreCount) {
+            List<File> storedFiles = findStoredFiles();
+
+            if (storedFiles.size() >= maxStoreCount) {
                 // Sort files then delete the first one (oldest timestamp)
-                Arrays.sort(files, comparator);
+                Collections.sort(storedFiles, comparator);
+                File oldestFile = storedFiles.get(0);
                 Logger.warn(String.format("Discarding oldest error as stored "
-                    + "error limit reached (%s)", files[0].getPath()));
-                if (!files[0].delete()) {
-                    files[0].deleteOnExit();
+                    + "error limit reached (%s)", oldestFile.getPath()));
+                if (!oldestFile.delete()) {
+                    oldestFile.deleteOnExit();
                 }
             }
         }