(#415) Add some additional context to error messages to distinguish whether loading data or parsing failed

Author: s1hofmann

Diff for: lib/imageResources.function.spec.ts

@@ -37,7 +37,7 @@ describe('fetchFromUrl', () => {
         const SUT = () => fetchFromUrl(malformedUrl);
 
         // THEN
-        await expect(SUT).rejects.toThrowError("Invalid URL");
+        await expect(SUT).rejects.toThrowError("Failed to fetch image data. Reason: Invalid URL");
     });
 
     it('should throw on non-image URLs', async () => {
@@ -48,7 +48,7 @@ describe('fetchFromUrl', () => {
         const SUT = () => fetchFromUrl(nonImageUrl);
 
         // THEN
-        await expect(SUT).rejects.toThrowError('Could not find MIME for Buffer');
+        await expect(SUT).rejects.toThrowError("Failed to parse image data. Reason: Could not find MIME for Buffer");
     });
 
     it('should return an RGB image from a valid URL', async () => {

Diff for: lib/imageResources.function.ts

@@ -22,8 +22,8 @@ export async function fetchFromUrl(url: string | URL): Promise<Image> {
     } else {
         try {
             imageUrl = new URL(url);
-        } catch (e) {
-            throw e;
+        } catch (e: any) {
+            throw new Error(`Failed to fetch image data. Reason: ${e.message}`);
         }
     }
     return Jimp.read(imageUrl.href)
@@ -38,6 +38,6 @@ export async function fetchFromUrl(url: string | URL): Promise<Image> {
             );
         })
         .catch(err => {
-            throw err;
+            throw new Error(`Failed to parse image data. Reason: ${err.message}`);
         });
 }