Exception handling for database queries

ref-test/app/tools/forms.py

@@ -1,7 +1,9 @@
 
 from ..extensions import db
+from ..tools.logs import write
 
 from flask import jsonify
+from sqlalchemy.exc import SQLAlchemyError
 from wtforms.validators import ValidationError
 
 import json
@@ -47,7 +49,10 @@ def get_time_options():
 
 def get_dataset_choices():
     from ..models import Dataset
-    datasets = Dataset.query.all()
+    try: datasets = Dataset.query.all()
+    except SQLAlchemyError as exception:
+        write('system.log', f'Database error when fetching dataset lists: {exception}')
+        return []
     dataset_choices = []
     for dataset in datasets:
         label = dataset.get_name()