feat: prevent runtime problems

src/body-parser.utils.ts

@@ -43,12 +43,14 @@ export function getIsEnabledBodyAs(enableTypes: BodyType[]) {
 export function getMimeTypes(
   extendTypes: NonNullable<BodyParserOptions['extendTypes']>,
 ) {
-  for (const extendedType of Object.keys(extendTypes) as BodyType[]) {
+  for (const extendedTypeKey of Object.keys(extendTypes) as BodyType[]) {
+    const extendedType = extendTypes[extendedTypeKey];
+
     if (
-      !supportedBodyTypes.includes(extendedType) ||
-      !Array.isArray(extendTypes[extendedType])
+      !supportedBodyTypes.includes(extendedTypeKey) ||
+      !Array.isArray(extendedType)
     ) {
-      throw new UnsupportedBodyTypeError(extendedType);
+      throw new UnsupportedBodyTypeError(extendedTypeKey);
     }
   }
 

test/middleware.test.ts

@@ -383,7 +383,7 @@ describe("test/body-parser.test.ts", () => {
       }
     });
 
-    it("should throw when pass supported type but with string value instead of array", () => {
+    it("should throw when pass supported types with string value instead of array", () => {
       try {
         createApp({
           extendTypes: {
@@ -394,6 +394,18 @@ describe("test/body-parser.test.ts", () => {
         expect(error instanceof UnsupportedBodyTypeError).toBe(true);
       }
     });
+
+    it("should throw when pass supported types with array contain falsy values", () => {
+      try {
+        createApp({
+          extendTypes: {
+            json: ["", 0, false, null, undefined],
+          } as any,
+        });
+      } catch (error) {
+        expect(error instanceof UnsupportedBodyTypeError).toBe(true);
+      }
+    });
   });
 
   describe("enableTypes", () => {
@@ -492,6 +504,7 @@ describe("test/body-parser.test.ts", () => {
         .send({ foo: "bar" })
         .expect(rawParsedBody, done);
     });
+
     it("shouldn't override koa request with raw request body if not exist and enableRawChecking is truthy", (done) => {
       const rawParsedBody = undefined;
       const app = createApp({ rawParsedBody, enableRawChecking: true });