Show error toasts on mobile share failures for easy debugging

Instead of requiring console access, surface all share failures as toasts:
- No canShare API available
- canShare test fails
- File sharing not supported
- Share API errors with error name

Makes debugging mobile issues visible on phone screen

Author: willuhmjs

src/lib/utils/download.ts

@@ -16,19 +16,36 @@ export async function downloadOrShare(fileId: string, filename?: string): Promis
 	// Desktop or no Share API support → traditional download
 	const isMobile = isMobileDevice();
 	const hasCanShare = typeof navigator.canShare === 'function';
-	const canShare = isMobile && hasCanShare && navigator.canShare({ files: [new File([], 'test')] });
 
-	console.log('[downloadOrShare]', {
-		fileId,
-		filename,
-		isMobile,
-		hasCanShare,
-		canShare,
-		userAgent: navigator.userAgent
-	});
+	console.log('[downloadOrShare] Detection:', { isMobile, hasCanShare });
 
-	if (!canShare) {
-		console.log('[downloadOrShare] Using window.open fallback');
+	if (!isMobile) {
+		console.log('[downloadOrShare] Desktop detected, using direct download');
+		window.open(fileUrl, '_blank');
+		return;
+	}
+
+	if (!hasCanShare) {
+		addToast('error', 'Web Share API not available on this browser');
+		console.log('[downloadOrShare] No canShare API, falling back');
+		window.open(fileUrl, '_blank');
+		return;
+	}
+
+	// Test if canShare works with files
+	let canShareFiles = false;
+	try {
+		canShareFiles = navigator.canShare({ files: [new File([], 'test')] });
+		console.log('[downloadOrShare] canShare test result:', canShareFiles);
+	} catch (e: any) {
+		console.error('[downloadOrShare] canShare test threw:', e);
+		addToast('error', `Share test failed: ${e.message || 'Unknown error'}`);
+		window.open(fileUrl, '_blank');
+		return;
+	}
+
+	if (!canShareFiles) {
+		addToast('error', 'File sharing not supported by this browser');
 		window.open(fileUrl, '_blank');
 		return;
 	}
@@ -44,11 +61,7 @@ export async function downloadOrShare(fileId: string, filename?: string): Promis
 		const blob = await response.blob();
 		const file = new File([blob], filename || 'download', { type: blob.type });
 
-		console.log('[downloadOrShare] Calling navigator.share with file:', {
-			name: file.name,
-			type: file.type,
-			size: file.size
-		});
+		console.log('[downloadOrShare] Sharing file:', file.name, file.type, file.size);
 
 		await navigator.share({ files: [file] });
 		console.log('[downloadOrShare] Share succeeded');
@@ -58,13 +71,13 @@ export async function downloadOrShare(fileId: string, filename?: string): Promis
 
 		// User cancelled the share sheet → AbortError (don't show error)
 		if (error.name === 'AbortError') {
-			console.log('[downloadOrShare] User cancelled share sheet');
+			console.log('[downloadOrShare] User cancelled');
 			return;
 		}
 
 		// Actual error → show toast with details
 		const message = error.message || 'Unknown error';
-		addToast('error', `Failed to share file: ${message}`);
+		addToast('error', `Share failed: ${message} (${error.name || 'no error name'})`);
 
 		// Fallback: try traditional download
 		console.log('[downloadOrShare] Falling back to window.open');