diff --git a/src/Logger.ts b/src/Logger.ts
index 5d8ba5a..61ea738 100644
--- a/src/Logger.ts
+++ b/src/Logger.ts
@@ -1,57 +1,15 @@
-export enum LogLevel {
-  TRACE = 10,
-  DEBUG = 20,
-  INFO = 30,
-  WARN = 40,
-  FATAL = 50,
-}
+import type {
+  LogOutputs,
+  LogContext,
+  BucketInfo,
+  LogMeta,
+  LogConfig,
+} from "./types/logger";
 
-enum LogLabel {
-  TRACE = "trace",
-  DEBUG = "debug",
-  INFO = "info",
-  WARN = "warn",
-  FATAL = "fatal",
-}
+import { LogLabel, LogLevel } from "./types/logger";
+import type { DeepRequired } from "generic";
 
-export interface TampermonkeyOutputOpts {
-  enabled: boolean;
-  maxBuckets?: number;
-  bucketIndexKey?: string;
-}
-
-export interface ConsoleOutputOpts {
-  enabled: boolean;
-}
-
-export interface LogOutputs {
-  console?: ConsoleOutputOpts;
-  tampermonkey?: TampermonkeyOutputOpts;
-  callback: ((message: string) => any) | undefined;
-}
-
-export interface LogConfig {
-  outputs?: LogOutputs;
-  bufferCapacity?: number;
-}
-
-export interface LogContext {
-  level?: number;
-  [key: string]: any;
-}
-
-interface LogMeta {
-  context: LogContext;
-  time: number;
-}
-
-interface BucketInfo {
-  name: string;
-  size: number;
-  createdAt: number;
-}
-
-const DEFAULT_OUTPUTS: Required<LogOutputs> = {
+const DEFAULT_OUTPUTS: DeepRequired<LogOutputs> = {
   console: { enabled: true },
   tampermonkey: {
     enabled: false,
@@ -60,10 +18,12 @@ const DEFAULT_OUTPUTS: Required<LogOutputs> = {
   },
   callback: undefined,
 };
-const DEFAULT_CONFIG: Required<LogConfig> = {
+
+const DEFAULT_CONFIG: DeepRequired<LogConfig> = {
   outputs: DEFAULT_OUTPUTS,
   bufferCapacity: 100_000,
 };
+
 const MESSAGE_STYLE = "background: inherit; color: inherit;";
 
 const STYLES = {
@@ -148,7 +108,7 @@ export function stringifyInstance(instance: {}) {
 }
 
 export function objectifyInstance(instance: any) {
-  let ret = {};
+  let ret: Record<string, any> = {};
   if (typeof instance !== "object") {
     ret[`${typeof instance}`] = instance;
   }
@@ -181,7 +141,7 @@ export class Logger {
   private buffer: string[];
   private bufferLength: number;
   private bucketIndex: BucketInfo[];
-  private outputs: Required<LogOutputs>;
+  private outputs: DeepRequired<LogOutputs>;
   private bufferCapacity: number;
 
   constructor(config: LogConfig = JSON.parse(JSON.stringify(DEFAULT_CONFIG))) {
@@ -260,8 +220,9 @@ export class Logger {
         this.flush();
       } else {
         while (this.bufferLength >= this.bufferCapacity) {
-          let stale = this.buffer.shift();
-          this.bufferLength -= stale.length;
+          const stale = this.buffer.shift();
+          const offset = stale ? stale.length : 0;
+          this.bufferLength -= offset;
         }
       }
     }
@@ -270,7 +231,7 @@ export class Logger {
   trace(message: string, context?: Object) {
     this.log(message, {
       level: LogLevel.TRACE,
-      stacktrace: new Error().stack.slice(13), // Remove the "Error\n    at "
+      stacktrace: new Error().stack?.slice(13), // Remove the "Error\n    at "
       ...context,
     });
   }
diff --git a/src/types/generic.ts b/src/types/generic.ts
new file mode 100644
index 0000000..5e83392
--- /dev/null
+++ b/src/types/generic.ts
@@ -0,0 +1,3 @@
+export type DeepRequired<T> = {
+  [K in keyof T]: DeepRequired<T[K]>;
+} & Required<T>;
diff --git a/src/types/logger.ts b/src/types/logger.ts
new file mode 100644
index 0000000..9ae1e06
--- /dev/null
+++ b/src/types/logger.ts
@@ -0,0 +1,52 @@
+export enum LogLevel {
+  TRACE = 10,
+  DEBUG = 20,
+  INFO = 30,
+  WARN = 40,
+  FATAL = 50,
+}
+
+export enum LogLabel {
+  TRACE = "trace",
+  DEBUG = "debug",
+  INFO = "info",
+  WARN = "warn",
+  FATAL = "fatal",
+}
+
+export interface TampermonkeyOutputOpts {
+  enabled: boolean;
+  maxBuckets?: number;
+  bucketIndexKey?: string;
+}
+
+export interface ConsoleOutputOpts {
+  enabled: boolean;
+}
+
+export interface LogOutputs {
+  console?: ConsoleOutputOpts;
+  tampermonkey?: TampermonkeyOutputOpts;
+  callback: ((message: string) => any) | undefined;
+}
+
+export interface LogConfig {
+  outputs?: LogOutputs;
+  bufferCapacity?: number;
+}
+
+export interface LogContext {
+  level?: number;
+  [key: string]: any;
+}
+
+export interface LogMeta {
+  context: LogContext;
+  time: number;
+}
+
+export interface BucketInfo {
+  name: string;
+  size: number;
+  createdAt: number;
+}
diff --git a/tsconfig.json b/tsconfig.json
index c46ae8f..184fe06 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -35,7 +35,7 @@
     } /* Specify a set of entries that re-map imports to additional lookup locations. */,
     // "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
     // "typeRoots": [],                                  /* Specify multiple folders that act like './node_modules/@types'. */
-    "types": ["tampermonkey"],
+    // "types": ["tampermonkey"],
     /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */