Add error handling

Check if service can initialize data source before making requests.

src/handlers.ts

@@ -138,15 +138,20 @@ export const handleGetCollection: Middleware = ({
 		};
 	}
 
-	await theResource.dataSource.initialize();
-	const resData = await theResource.dataSource.getMultiple(); // TODO paginated responses per resource
-	const theFormatted = theSerializerPair.serialize(resData);
+	try {
+		await theResource.dataSource.initialize();
+		const resData = await theResource.dataSource.getMultiple(); // TODO paginated responses per resource
+		const theFormatted = theSerializerPair.serialize(resData);
 
-	res.writeHead(constants.HTTP_STATUS_OK, {
-		'Content-Type': theMediaType,
-		'X-Resource-Total-Item-Count': resData.length
-	});
-	res.end(theFormatted);
+		res.writeHead(constants.HTTP_STATUS_OK, {
+			'Content-Type': theMediaType,
+			'X-Resource-Total-Item-Count': resData.length
+		});
+		res.end(theFormatted);
+	} catch {
+		res.statusCode = constants.HTTP_STATUS_INTERNAL_SERVER_ERROR;
+		res.end();
+	}
 
 	return {
 		handled: true
@@ -201,23 +206,31 @@ export const handleGetItem: Middleware = ({
 		};
 	}
 
-	await theResource.dataSource.initialize();
-	const singleResDatum = await theResource.dataSource.getSingle(mainResourceId);
-	if (singleResDatum) {
-		const theFormatted = theSerializerPair.serialize(singleResDatum);
-		res.writeHead(constants.HTTP_STATUS_OK, { 'Content-Type': theMediaType });
-		res.end(theFormatted);
+	try {
+		await theResource.dataSource.initialize();
+		const singleResDatum = await theResource.dataSource.getSingle(mainResourceId);
+		if (singleResDatum) {
+			const theFormatted = theSerializerPair.serialize(singleResDatum);
+			res.writeHead(constants.HTTP_STATUS_OK, {'Content-Type': theMediaType});
+			res.end(theFormatted);
+			return {
+				handled: true
+			};
+		}
+
+		res.statusCode = constants.HTTP_STATUS_NOT_FOUND;
+		res.statusMessage = `${theResource.itemName} Not Found`;
+		res.end();
+		return {
+			handled: true
+		};
+	} catch {
+		res.statusCode = constants.HTTP_STATUS_INTERNAL_SERVER_ERROR;
+		res.end();
 		return {
 			handled: true
 		};
 	}
-
-	res.statusCode = constants.HTTP_STATUS_NOT_FOUND;
-	res.statusMessage = `${theResource.itemName} Not Found`;
-	res.end();
-	return {
-		handled: true
-	};
 };
 
 
@@ -271,8 +284,8 @@ export const handleDeleteItem: Middleware = ({
 		}
 	}
 
-	await theResource.dataSource.initialize();
 	try {
+		await theResource.dataSource.initialize();
 		const response = await theResource.dataSource.delete(mainResourceId);
 		if (typeof response !== 'undefined' && !response && theResource.throws404OnDeletingNotFound) {
 			res.statusCode = constants.HTTP_STATUS_NOT_FOUND;