json: fix min 0

common/json-schema-to-grammar.cpp

@@ -195,6 +195,7 @@ static void _generate_min_max_int(int min_value, int max_value, std::stringstrea
         if (min_value == 0) {
             if (top_level) {
                 out << "[1-9] ";
+                out << "[0] | [1-9] ";
                 more_digits(0, less_decimals);
             } else {
                 more_digits(1, decimals_left);

tests/test-json-schema-to-grammar.cpp

@@ -88,7 +88,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "minimum": 0
         })""",
         R"""(
-            root ::= ([1-9] [0-9]{0,15}) space
+            root ::= ([0] | [1-9] [0-9]{0,15}) space
             space ::= " "?
         )"""
     });