fix: handle invalid lucene query term values gracefully (#268)

Handle invalid Lucene query term values gracefully to prevent HTTP 500
errors.
fixes: #253

app/api.py

@@ -112,7 +112,7 @@ def status_for_response(result: SearchResponse):
 @app.post("/search")
 def search(
     response: Response, search_parameters: Annotated[PostSearchParameters, Body()]
-):
+) -> SearchResponse:
     """This is the main search endpoint.
 
     It uses POST request to ensure privacy.

app/search.py

@@ -4,13 +4,16 @@
 from . import config
 from ._types import (
     DebugInfo,
+    ErrorSearchResponse,
     QueryAnalysis,
     SearchParameters,
     SearchResponse,
     SearchResponseDebug,
+    SearchResponseError,
     SuccessSearchResponse,
 )
 from .charts import build_charts
+from .exceptions import QueryCheckError
 from .facets import build_facets
 from .postprocessing import BaseResultProcessor, load_result_processor
 from .query import build_elasticsearch_query_builder, build_search_query, execute_query
@@ -79,12 +82,18 @@ def search(
         params.charts,
     )
     index_config = params.index_config
-    query = build_search_query(
-        params,
-        # ES query builder is generated from elasticsearch mapping and
-        # takes ~40ms to generate, build-it before hand to avoid this delay
-        es_query_builder=get_es_query_builder(params.valid_index_id),
-    )
+    try:
+        query = build_search_query(
+            params,
+            # ES query builder is generated from elasticsearch mapping and
+            # takes ~40ms to generate, build-it before hand to avoid this delay
+            es_query_builder=get_es_query_builder(params.valid_index_id),
+        )
+    except QueryCheckError as e:
+        return ErrorSearchResponse(
+            debug=SearchResponseDebug(),
+            errors=[SearchResponseError(title="QueryCheckError", description=str(e))],
+        )
     (
         logger.debug(
             "Luqum query: %s\nElasticsearch query: %s",