chore: make fn parameter required

Author: maxmorozoff

README.md

@@ -483,7 +483,7 @@ type Result<T, E = Error> = ([data: T, error: null] | [data: null, error: E]) &
 ### Edge Cases
 
 ```ts
-tryCatch(); // Returns [undefined, null]
+tryCatch(undefined); // Returns [undefined, null]
 tryCatch(null); // Returns [null, null]
 tryCatch(() => {
   throw new Error("Unexpected Error");

packages/try-catch-tuple/README.md

@@ -266,7 +266,7 @@ type Result<T, E = Error> = [data: T, error: null] | [data: null, error: E];
 ## Edge Cases
 
 ```ts
-tryCatch(); // Returns [undefined, null]
+tryCatch(undefined); // Returns [undefined, null]
 tryCatch(null); // Returns [null, null]
 tryCatch(() => {
   throw new Error("Unexpected Error");

packages/try-catch-tuple/src/tryCatch.ts

@@ -8,7 +8,7 @@ type TryCatchResult<T, E extends Error> = T extends Promise<infer U>
   : Result<T, E>;
 
 type TryCatchFunc<E_ extends Error = Error> = <T, E extends Error = E_>(
-  fn?: T | (() => T),
+  fn: T | (() => T),
   operationName?: string,
 ) => TryCatchResult<T, E>;
 
@@ -36,7 +36,7 @@ type TryCatch<
  * @returns A Result, or a Promise resolving to a Result, depending on fn.
  */
 export const tryCatch: TryCatch = <T, E extends Error = Error>(
-  fn?: T | (() => T),
+  fn: T | (() => T),
   operationName?: string,
 ) => {
   try {

packages/try-catch-tuple/tests/tryCatch.test.ts

@@ -344,7 +344,8 @@ describe("tryCatch", () => {
 
   describe("edge cases", () => {
     test("should handle undefined fn", () => {
-      const [result, error] = tryCatch();
+      const [result, error] = tryCatch(undefined);
+      if (error) expect.unreachable();
       expect(result).toBe(undefined);
       expect(error).toBeNil();
     });