Find Tutors fails to match requested subject

[derek-rogers]

• When searching for 'history' only, the backend logs the following:

Subjects to find:  [ 'history' ]
tutors:  []

• However, when searching for 'history' and 'english', a tutor with 'history' is found:

Subjects to find:  [ 'history', 'english' ]
tutors:  [ { _id: 5bff2f343653a00a9c94ca3f,
    name: 'test',
    email: '3@test.com',
    gradeLevel: '9',
    userType: 'tutor',
    password: '$2a$10$ogdZPyB0NvuusoGQT4UtY.9TjfeYN6sY.IRbm0Jqqyw4h9dhzVWTO',
    __v: 0,
    subjects: [ 'english', 'history', 'science', 'math' ] } ]