Fix CircleCI build failing on master branch

[thani-sh]

CircleCI build fails on master branch.

#!/bin/bash -eo pipefail
npm install
npm WARN prepublish-on-install As of npm@5, `prepublish` scripts are deprecated.
npm WARN prepublish-on-install Use `prepare` for build steps and `prepublishOnly` for upload-only.
npm WARN prepublish-on-install See the deprecation note in `npm help scripts` for more information.
> @creately/mungo@1.2.1 prepublish /home/circleci/repo

> npm run lint && npm run build
> @creately/mungo@1.2.1 lint /home/circleci/repo

> prettier --print-width 120 --single-quote --trailing-comma es5 --write "src/**/*.ts"
src/__module.d.tssrc/__module.d.ts 156ms

src/__tests.tssrc/__tests.ts 12ms

src/framework/tests/pathutil.spec.tssrc/framework/tests/pathutil.spec.ts 195ms

src/framework/tests/typeutil.spec.tssrc/framework/tests/typeutil.spec.ts 39ms

src/framework/modifier.tssrc/framework/modifier.ts 16ms

src/framework/operator.tssrc/framework/operator.ts 18ms

src/framework/pathutil.tssrc/framework/pathutil.ts 30ms

src/framework/typeutil.tssrc/framework/typeutil.ts 11ms

src/framework/validator.tssrc/framework/validator.ts 8ms

src/index.tssrc/index.ts 3ms

src/invert.tssrc/invert.ts 9ms

src/modify.tssrc/modify.ts 7ms

src/operators/tests/__testutils.tssrc/operators/tests/__testutils.ts 24ms

src/operators/tests/arrays.$pull.spec.tssrc/operators/tests/arrays.$pull.spec.ts 28ms

src/operators/tests/arrays.$push.spec.tssrc/operators/tests/arrays.$push.spec.ts 16ms

src/operators/tests/fields.$set.spec.tssrc/operators/tests/fields.$set.spec.ts 13ms

src/operators/arrays.tssrc/operators/arrays.ts 14ms

src/operators/fields.tssrc/operators/fields.ts 13ms

src/operators/index.tssrc/operators/index.ts 3ms
> @creately/mungo@1.2.1 build /home/circleci/repo

> tsc
node_modules/@types/node/index.d.ts:252:13 - error TS2403: Subsequent variable declarations must have the same type.  Variable 'require' must be of type 'any', but here has type 'NodeRequire'.
252 declare var require: NodeRequire;

~~~~~~~
Found 1 error.
npm ERR! code ELIFECYCLE

npm ERR! errno 2

npm ERR! @creately/mungo@1.2.1 build: tsc

npm ERR! Exit status 2

npm ERR!

npm ERR! Failed at the @creately/mungo@1.2.1 build script.

npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:

npm ERR!     /home/circleci/.npm/_logs/2018-12-07T09_49_59_135Z-debug.log

npm ERR! code ELIFECYCLE

npm ERR! errno 2

npm ERR! @creately/mungo@1.2.1 prepublish: npm run lint && npm run build

npm ERR! Exit status 2

npm ERR!

npm ERR! Failed at the @creately/mungo@1.2.1 prepublish script.

npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:

npm ERR!     /home/circleci/.npm/_logs/2018-12-07T09_49_59_174Z-debug.log

Exited with code 2