Wire up error handlers.

Replace some 400s with more appropriate 500s.

DAO methods that cause unexpected exceptions get caught and
logged by errors.py 500 error handler.

app/errors.py

@@ -1,36 +1,34 @@
-from flask import (jsonify, current_app)
-
-from app.main import main
+from flask import (
+    jsonify,
+    current_app
+)
 
 
-@main.app_errorhandler(400)
-def bad_request(e):
-    return jsonify(error=str(e.description)), 400
+def register_errors(blueprint):
 
+    @blueprint.app_errorhandler(400)
+    def bad_request(e):
+        return jsonify(error=str(e.description)), 400
 
-@main.app_errorhandler(401)
-def unauthorized(e):
-    error_message = "Unauthorized, authentication token must be provided"
-    return jsonify(error=error_message), 401, [('WWW-Authenticate', 'Bearer')]
+    @blueprint.app_errorhandler(401)
+    def unauthorized(e):
+        error_message = "Unauthorized, authentication token must be provided"
+        return jsonify(error=error_message), 401, [('WWW-Authenticate', 'Bearer')]
 
+    @blueprint.app_errorhandler(403)
+    def forbidden(e):
+        error_message = "Forbidden, invalid authentication token provided"
+        return jsonify(error=error_message), 403
 
-@main.app_errorhandler(403)
-def forbidden(e):
-    error_message = "Forbidden, invalid authentication token provided"
-    return jsonify(error=error_message), 403
+    @blueprint.app_errorhandler(404)
+    def page_not_found(e):
+        return jsonify(error=e.description or "Not found"), 404
 
+    @blueprint.app_errorhandler(429)
+    def limit_exceeded(e):
+        return jsonify(error=str(e.description)), 429
 
-@main.app_errorhandler(404)
-def page_not_found(e):
-    return jsonify(error=e.description or "Not found"), 404
-
-
-@main.app_errorhandler(429)
-def limit_exceeded(e):
-    return jsonify(error=str(e.description)), 429
-
-
-@main.app_errorhandler(500)
-def internal_server_error(e):
-    current_app.logger.exception(e)
-    return jsonify(error="Internal error"), 500
+    @blueprint.app_errorhandler(500)
+    def internal_server_error(e):
+        current_app.logger.exception(e)
+        return jsonify(error="Internal error"), 500