Added a safeguard for too small images (#14)

src/services/converters/ImageMediaConverter.ts

@@ -1,8 +1,9 @@
 import MediaConverter, { MediaFile } from "./MediaConverter";
 
 const MAX_IMAGE_DIM = 1024;
-
-type ImageErrorReason = "invalid" | "too large";
+const MIN_IMAGE_DIM = 3;
+type ImageSizeErrorReason = "too large" | "too small";
+type ImageErrorReason = "invalid" | ImageSizeErrorReason;
 
 class ImageError extends Error {
   public readonly reason: ImageErrorReason;
@@ -14,19 +15,26 @@ class ImageError extends Error {
   }
 }
 
+type ImageCheckResult = "ok" | ImageSizeErrorReason;
 export default class ImageMediaConverter extends MediaConverter {
-  async checkImage(file: Blob): Promise<boolean> {
+  async checkImage(file: Blob): Promise<ImageCheckResult> {
     const image = await createImageBitmap(file);
-    return image.width <= MAX_IMAGE_DIM && image.height <= MAX_IMAGE_DIM;
+    if (image.width > MAX_IMAGE_DIM || image.height > MAX_IMAGE_DIM)
+      return "too large";
+
+    if (image.width < MIN_IMAGE_DIM || image.height < MIN_IMAGE_DIM)
+      return "too small";
+
+    return "ok";
   }
 
   async convert(files: MediaFile[]): Promise<MediaFile[]> {
     const body = new FormData();
 
     for (const file of files) {
       try {
-        if (!(await this.checkImage(file.data)))
-          throw new ImageError("too large");
+        const checkResult = await this.checkImage(file.data);
+        if (checkResult !== "ok") throw new ImageError(checkResult);
 
         body.append(file.filepath, file.data);
       } catch (error) {