chore: print human-readable error if index.html isn't found (#788)

Signed-off-by: Dorian Johnson <2020@dorianj.net>

amundsen_application/api/__init__.py

@@ -2,11 +2,15 @@
 # SPDX-License-Identifier: Apache-2.0
 
 from typing import Any, Tuple
+import logging
 
 from flask import Flask, render_template
+import jinja2
 import os
 
+
 ENVIRONMENT = os.getenv('APPLICATION_ENV', 'development')
+LOGGER = logging.getLogger(__name__)
 
 
 def init_routes(app: Flask) -> None:
@@ -16,7 +20,11 @@ def init_routes(app: Flask) -> None:
 
 
 def index(path: str) -> Any:
-    return render_template("index.html", env=ENVIRONMENT)  # pragma: no cover
+    try:
+        return render_template("index.html", env=ENVIRONMENT)  # pragma: no cover
+    except jinja2.exceptions.TemplateNotFound as e:
+        LOGGER.error("index.html template not found, have you built the front-end JS (npm run build in static/?")
+        raise e
 
 
 def healthcheck() -> Tuple[str, int]: