RediSearch query error reporting (#925)

docs/commands.md

@@ -660,7 +660,7 @@ GRAPH.QUERY DEMO_GRAPH "DROP INDEX ON :person(age)"
 
 ## Full-text indexes
 
-RedisGraph leverages the indexing capabilities of RediSearch to provide full-text indexes through procedure calls. To construct a full-text index on the `title` property of all nodes with label `movie`, use the syntax:
+RedisGraph leverages the indexing capabilities of [RediSearch](https://oss.redislabs.com/redisearch/index.html) to provide full-text indices through procedure calls. To construct a full-text index on the `title` property of all nodes with label `movie`, use the syntax:
 
 ```sh
 GRAPH.QUERY DEMO_GRAPH "CALL db.idx.fulltext.createNodeIndex('movie', 'title')"

src/procedures/proc_fulltext_query.c

@@ -55,6 +55,19 @@ ProcedureResult Proc_FulltextQueryNodeInvoke(ProcedureCtx *ctx, const SIValue *a
 
 	// Execute query
 	pdata->iter = Index_Query(pdata->idx, query, &err);
+	// Raise runtime exception if err != NULL.
+	if(err) {
+		/* RediSearch error message is allocated using `rm_strdup`
+		 * QueryCtx is expecting to free `error` using `free`
+		 * in which case we have no option but to clone error. */
+		char *error;
+		asprintf(&error, "RediSearch: %s", err);
+		rm_free(err);
+		QueryCtx_SetError(error);
+		/* Raise the exception, we expect an exception handler to be set.
+		 * as procedure invocation is done at runtime. */
+		QueryCtx_RaiseRuntimeException();
+	}
 	assert(pdata->iter);
 
 	ctx->privateData = pdata;

src/value.c

@@ -398,7 +398,7 @@ SIValue SIValue_Modulo(const SIValue a, const SIValue n) {
 	case true:
 		// The modulo machine instruction may be used if a and n are both integers.
 		return SI_LongVal(a.longval % n.longval);
-	case false:
+	default:
 		// Otherwise, use the library function fmod to calculate the modulo and return a double.
 		return SI_DoubleVal(fmod(SI_GET_NUMERIC(a), SI_GET_NUMERIC(n)));
 	}

tests/flow/test_procedures.py

@@ -286,4 +286,12 @@ def test_procedure_propertyKeys(self):
         actual_resultset = redis_graph.call_procedure("db.propertyKeys").result_set
         expected_results = [["name"], ["value"]]
         self.env.assertEquals(actual_resultset, expected_results)
-
+
+    def test_procedure_fulltext_syntax_error(self):
+        try:
+            query = """CALL db.idx.fulltext.queryNodes('fruit', 'Orange || Apple') YIELD node RETURN node"""
+            redis_graph.query(query)
+            assert(False)
+        except redis.exceptions.ResponseError:
+            # Expecting an error.
+            pass