Do not attempt to read a folder as if it were a file

[Li0liQ]

Sometimes stricter confuses folders and files and tries to perform illegal operations on them:

Error: EISDIR: illegal operation on a directory, read
    at tryReadSync (fs.js:332:20)
    at Object.readSync (fs.js:498:3)
    at Object.readFileSync (fs.js:369:19)
    at readFile (/Users/user/project/node_modules/stricter/lib/index.js:31:26)
    at readFileData (/Users/user/project/node_modules/stricter/lib/index.js:484:18)
    at files.reduce (/Users/user/project/node_modules/stricter/lib/index.js:526:21)
    at Array.reduce (<anonymous>)
    at processFiles (/Users/user/project/node_modules/stricter/lib/index.js:525:27)
    at parseDependencies (/Users/user/project/node_modules/stricter/lib/index.js:1419:21)
    at getDependantHash (/Users/user/project/scripts/common/dependencies-analysis/index.js:58:26)
    at getImplicitlyModifiedFiles (/Users/user/project/scripts/common/files/get-affected-files.js:43:27)
    at getAffectedFiles (/Users/user/project/scripts/common/files/get-affected-files.js:128:72)
    at getAffectedApps (/Users/user/project/scripts/dependencies/dependency-bump/get-affected-apps.js:41:27)
    at Object.<anonymous> (/Users/user/project/scripts/dependencies/dependency-bump/get-affected-apps.js:50:32)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)