Return false for contains(string, non-string) instead of raising TypeError

[gaoflow]

Summary

contains() with a string subject and a non-string search raises an uncaught TypeError instead of returning false:

import jmespath
jmespath.search("contains(@, `123`)", "foobar")
# TypeError: 'in <string>' requires string as left operand, not int

This contradicts the JMESPath spec, which defines contains('foobar', 123) → false. It affects any non-string search against a string subject — number, boolean, null, array, or object.

The array case already returns false for a type-mismatched search of any type (contains([1,2,3], false) → false), because Python's in on a list accepts any right-hand type. Only the string path was inconsistent, since 123 in "foobar" raises.

Cause

Functions._func_contains was simply:

@signature({'types': ['array', 'string']}, {'types': []})
def _func_contains(self, subject, search):
    return search in subject

The signature permits a search of any type, but search in subject raises TypeError when subject is a string and search is not.

Fix

Guard the membership test: when the subject is a string and the search is not, return false (a non-string can never be a substring of a string). This brings the string path in line with the array path and the spec.

Verification

• Added compliance cases for number, boolean and null searches against a string subject (tests/compliance/functions.json), each expecting false. They fail with TypeError before the fix and pass after (confirmed via git stash).
• String-in-string and all array-membership behavior is unchanged.
• Full suite: 994 passed, 1 skipped (was 991 + 1 skipped).

This pull request was prepared with the assistance of AI, under my direction and review.