fix(media): harden unknown mime handling from #39199 (thanks @nicolasgrasset)

Co-authored-by: Nicolas Grasset <nicolas.grasset@gmail.com>

src/media/constants.ts

@@ -3,11 +3,11 @@ export const MAX_AUDIO_BYTES = 16 * 1024 * 1024; // 16MB
 export const MAX_VIDEO_BYTES = 16 * 1024 * 1024; // 16MB
 export const MAX_DOCUMENT_BYTES = 100 * 1024 * 1024; // 100MB
 
-export type MediaKind = "image" | "audio" | "video" | "document" | "unknown";
+export type MediaKind = "image" | "audio" | "video" | "document";
 
-export function mediaKindFromMime(mime?: string | null): MediaKind {
+export function mediaKindFromMime(mime?: string | null): MediaKind | undefined {
   if (!mime) {
-    return "unknown";
+    return undefined;
   }
   if (mime.startsWith("image/")) {
     return "image";
@@ -27,7 +27,7 @@ export function mediaKindFromMime(mime?: string | null): MediaKind {
   if (mime.startsWith("application/")) {
     return "document";
   }
-  return "unknown";
+  return undefined;
 }
 
 export function maxBytesForKind(kind: MediaKind): number {

src/media/mime.test.ts

@@ -128,7 +128,9 @@ describe("mediaKindFromMime", () => {
     { mime: "text/plain", expected: "document" },
     { mime: "text/csv", expected: "document" },
     { mime: "text/html; charset=utf-8", expected: "document" },
-    { mime: "model/gltf+json", expected: "unknown" },
+    { mime: "model/gltf+json", expected: undefined },
+    { mime: null, expected: undefined },
+    { mime: undefined, expected: undefined },
   ] as const)("classifies $mime", ({ mime, expected }) => {
     expect(mediaKindFromMime(mime)).toBe(expected);
   });
@@ -136,4 +138,9 @@ describe("mediaKindFromMime", () => {
   it("normalizes MIME strings before kind classification", () => {
     expect(kindFromMime(" Audio/Ogg; codecs=opus ")).toBe("audio");
   });
+
+  it("returns undefined for missing or unrecognized MIME kinds", () => {
+    expect(kindFromMime(undefined)).toBeUndefined();
+    expect(kindFromMime("model/gltf+json")).toBeUndefined();
+  });
 });

src/media/mime.ts

@@ -187,6 +187,6 @@ export function imageMimeFromFormat(format?: string | null): string | undefined
   }
 }
 
-export function kindFromMime(mime?: string | null): MediaKind {
+export function kindFromMime(mime?: string | null): MediaKind | undefined {
   return mediaKindFromMime(normalizeMimeType(mime));
 }