function getFileContentsForFile(filePath) {
    if (projectCache[filePath] || projectCache[filePath] === "") {
        return projectCache[filePath];
    }
    try {
        if (getFilesizeInBytes(filePath) <= MAX_FILE_SIZE_TO_INDEX) {
            projectCache[filePath] = fs.readFileSync(filePath, 'utf8');
        } else {
            projectCache[filePath] = "";
        }
    } catch (ex) {
        console.log(ex);
        projectCache[filePath] = null;
    }
    return projectCache[filePath];
}
Get the contents of a file from cache given the path. Also adds the file contents to cache from disk if not cached.
Will not read/cache files greater than MAX_FILE_SIZE_TO_INDEX in size.
@param   {string} filePath full file path
@return {string} contents or null if no contents