Fix error type (Error -> unknown) (#235)

Author: bvaughn

README.md

@@ -63,7 +63,7 @@ None
     <tr>
       <td>onError</td>
       <td><p>Optional callback to enable e.g. logging error information to a server.
-@param error Error that was thrown
+@param error Value that was thrown; typically an instance of <code>Error</code>
 @param info React &quot;component stack&quot; identifying where the error was thrown</p>
 </td>
     </tr>

lib/components/ErrorBoundary.test.tsx

@@ -16,6 +16,7 @@ import type {
   FallbackProps,
   OnErrorCallback,
 } from "../types";
+import { getErrorMessage } from "../utils/getErrorMessage";
 
 describe("ErrorBoundary", () => {
   let container: HTMLDivElement;
@@ -84,7 +85,7 @@ describe("ErrorBoundary", () => {
       render({ onError });
 
       expect(onError).toHaveBeenCalledTimes(1);
-      expect(onError.mock.calls[0][0].message).toEqual("💥💥💥");
+      expect(getErrorMessage(onError.mock.calls[0][0])).toEqual("💥💥💥");
     });
 
     it('should call "onReset" when boundary reset via imperative API', () => {
@@ -169,7 +170,7 @@ describe("ErrorBoundary", () => {
 
   describe('"FallbackComponent"', () => {
     let fallbackComponent: Mock<(props: FallbackProps) => ReactElement>;
-    let lastRenderedError: Error | null = null;
+    let lastRenderedError: unknown | null = null;
     let lastRenderedResetErrorBoundary:
       | FallbackProps["resetErrorBoundary"]
       | null = null;
@@ -204,7 +205,7 @@ describe("ErrorBoundary", () => {
     it("should render fallback in the event of an error", () => {
       shouldThrow = true;
       render();
-      expect(lastRenderedError?.message).toBe("💥💥💥");
+      expect(getErrorMessage(lastRenderedError)).toBe("💥💥💥");
       expect(container.textContent).toBe("FallbackComponent");
     });
 
@@ -235,7 +236,7 @@ describe("ErrorBoundary", () => {
   });
 
   describe('"fallbackRender" render prop', () => {
-    let lastRenderedError: Error | null = null;
+    let lastRenderedError: unknown | null = null;
     let lastRenderedResetErrorBoundary:
       | FallbackProps["resetErrorBoundary"]
       | null = null;
@@ -271,15 +272,15 @@ describe("ErrorBoundary", () => {
     it("should render fallback in the event of an error", () => {
       shouldThrow = true;
       render();
-      expect(lastRenderedError?.message).toBe("💥💥💥");
+      expect(getErrorMessage(lastRenderedError)).toBe("💥💥💥");
       expect(fallbackRender).toHaveBeenCalled();
       expect(container.textContent).toBe("fallbackRender");
     });
 
     it("should re-render children if boundary is reset via prop", () => {
       shouldThrow = true;
       render();
-      expect(lastRenderedError?.message).toBe("💥💥💥");
+      expect(getErrorMessage(lastRenderedError)).toBe("💥💥💥");
       expect(fallbackRender).toHaveBeenCalled();
       expect(container.textContent).toBe("fallbackRender");
 
@@ -295,7 +296,7 @@ describe("ErrorBoundary", () => {
     it("should re-render children if boundary is reset reset keys", () => {
       shouldThrow = true;
       render({ resetKeys: [1] });
-      expect(lastRenderedError?.message).toBe("💥💥💥");
+      expect(getErrorMessage(lastRenderedError)).toBe("💥💥💥");
       expect(fallbackRender).toHaveBeenCalled();
       expect(container.textContent).toBe("fallbackRender");
 
@@ -306,7 +307,7 @@ describe("ErrorBoundary", () => {
   });
 
   describe("thrown values", () => {
-    let lastRenderedError: Error | null = null;
+    let lastRenderedError: unknown | null = null;
     let fallbackRender: (props: FallbackProps) => ReactElement;
     let onError: Mock<(...args: unknown[]) => unknown>;
 

lib/components/ErrorBoundary.tsx

@@ -7,7 +7,7 @@ const isDevelopment = import.meta.env.DEV;
 type ErrorBoundaryState =
   | {
       didCatch: true;
-      error: Error;
+      error: unknown;
     }
   | {
       didCatch: false;
@@ -63,7 +63,7 @@ export class ErrorBoundary extends Component<
     }
   }
 
-  componentDidCatch(error: Error, info: ErrorInfo) {
+  componentDidCatch(error: unknown, info: ErrorInfo) {
     this.props.onError?.(error, info);
   }
 

lib/context/ErrorBoundaryContext.ts

@@ -2,7 +2,7 @@ import { createContext } from "react";
 
 export type ErrorBoundaryContextType = {
   didCatch: boolean;
-  error: Error | null;
+  error: unknown | null;
   resetErrorBoundary: (...args: unknown[]) => void;
 };
 

lib/hooks/useErrorBoundary.test.tsx

@@ -3,6 +3,7 @@ import { createRoot } from "react-dom/client";
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import { ErrorBoundary } from "../components/ErrorBoundary";
 import { assert } from "../utils/assert";
+import { getErrorMessage } from "../utils/getErrorMessage";
 import { useErrorBoundary, type UseErrorBoundaryApi } from "./useErrorBoundary";
 
 describe("useErrorBoundary", () => {
@@ -41,7 +42,9 @@ describe("useErrorBoundary", () => {
 
     render(
       <ErrorBoundary
-        fallbackRender={({ error }) => <div>Fallback: {error.message}</div>}
+        fallbackRender={({ error }) => (
+          <div>Fallback: {getErrorMessage(error)}</div>
+        )}
       >
         <Child />
       </ErrorBoundary>,

lib/hooks/useErrorBoundary.ts

@@ -3,13 +3,13 @@ import { ErrorBoundaryContext } from "../context/ErrorBoundaryContext";
 import { assertErrorBoundaryContext } from "../utils/assertErrorBoundaryContext";
 
 type UseErrorBoundaryState =
-  | { error: Error; hasError: true }
+  | { error: unknown; hasError: true }
   | { error: null; hasError: false };
 
 export type UseErrorBoundaryApi = {
-  error: Error | null;
+  error: unknown | null;
   resetBoundary: () => void;
-  showBoundary: (error: Error) => void;
+  showBoundary: (error: unknown) => void;
 };
 
 /**
@@ -21,7 +21,7 @@ export function useErrorBoundary(): {
   /**
    * The currently visible `Error` (if one has been thrown).
    */
-  error: Error | null;
+  error: unknown | null;
 
   /**
    * Method to reset and retry the nearest active error boundary (if one is active).
@@ -35,7 +35,7 @@ export function useErrorBoundary(): {
    * Errors thrown in event handlers, or after async code has run, will not be caught.
    * This method is a way to imperatively trigger an error boundary during these phases.
    */
-  showBoundary: (error: Error) => void;
+  showBoundary: (error: unknown) => void;
 } {
   const context = useContext(ErrorBoundaryContext);
 
@@ -55,7 +55,7 @@ export function useErrorBoundary(): {
         resetErrorBoundary();
         setState({ error: null, hasError: false });
       },
-      showBoundary: (error: Error) =>
+      showBoundary: (error: unknown) =>
         setState({
           error,
           hasError: true,

lib/index.ts

@@ -3,6 +3,7 @@
 export { ErrorBoundary } from "./components/ErrorBoundary";
 export { ErrorBoundaryContext } from "./context/ErrorBoundaryContext";
 export { useErrorBoundary } from "./hooks/useErrorBoundary";
+export { getErrorMessage } from "./utils/getErrorMessage";
 export { withErrorBoundary } from "./utils/withErrorBoundary";
 
 export type { ErrorBoundaryContextType } from "./context/ErrorBoundaryContext";

lib/types.ts

@@ -6,20 +6,20 @@ import type {
 } from "react";
 
 export type FallbackProps = {
-  error: Error;
+  error: unknown;
   resetErrorBoundary: (...args: unknown[]) => void;
 };
 
-export type OnErrorCallback = (error: Error, info: ErrorInfo) => void;
+export type OnErrorCallback = (error: unknown, info: ErrorInfo) => void;
 
 type ErrorBoundarySharedProps = PropsWithChildren<{
   /**
    * Optional callback to enable e.g. logging error information to a server.
    *
-   * @param error Error that was thrown
+   * @param error Value that was thrown; typically an instance of `Error`
    * @param info React "component stack" identifying where the error was thrown
    */
-  onError?: (error: Error, info: ErrorInfo) => void;
+  onError?: (error: unknown, info: ErrorInfo) => void;
 
   /**
    * Optional callback to to be notified when an error boundary is "reset" so React can retry the failed render.

lib/utils/getErrorMessage.ts

@@ -0,0 +1,17 @@
+export function getErrorMessage(thrown: unknown): string | undefined {
+  switch (typeof thrown) {
+    case "object": {
+      if (
+        thrown !== null &&
+        "message" in thrown &&
+        typeof thrown.message === "string"
+      ) {
+        return thrown.message;
+      }
+      break;
+    }
+    case "string": {
+      return thrown;
+    }
+  }
+}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-error-boundary",
-  "version": "6.0.3",
+  "version": "6.0.4",
   "type": "module",
   "description": "Simple reusable React error boundary component",
   "author": "Brian Vaughn <brian.david.vaughn@gmail.com>",