Fix off-by-one on number of backup files

Author: sam-lord

lib/fileRotator.js

@@ -116,14 +116,15 @@ class FileRotator extends EventEmitter {
 
     async _deleteFiles() {
         const filesToDelete = [];
-        let fileNumber = 0;
+        // Only count backups - start at file 1 to ignore current file
+        let fileNumber = 1;
         let bytesTotal = 0;
         for (; ; fileNumber++) {
             const name = this._getFileName(fileNumber, true);
             try {
                 const result = await fs.stat(name);
                 bytesTotal += result.size;
-                if ((this._totalSize && bytesTotal > this._totalSize) || (this._totalFiles && fileNumber > this._totalFiles)) {
+                if ((this._totalSize && bytesTotal > this._totalSize) || (this._totalFiles && fileNumber >= this._totalFiles)) {
                     filesToDelete.push(name);
                 }
             } catch (err) {