Fix type check errors

[ghost]

Q	A
Bug fix?	no
Breaking change?	no
New feature?	no
Deprecations?	no
Spec compliancy?	no
Tests added/pass?	Tests pass
Fixed tickets
License	MIT

Fixed new type checking errors due to #489 and #488 being merged.

[codecov]

Codecov Report

Merging #521 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #521   +/-   ##
=======================================
  Coverage   98.27%   98.27%           
=======================================
  Files          22       22           
  Lines        3530     3530           
  Branches      981      981           
=======================================
  Hits         3469     3469           
  Misses         22       22           
  Partials       39       39

Flag	Coverage Δ
#babel	81.04% <80%> (ø)	⬆️
#babylon	97.11% <100%> (ø)	⬆️

Impacted Files	Coverage Δ
src/parser/statement.js	99.08% <100%> (ø)	⬆️
src/plugins/estree.js	99.16% <100%> (ø)	⬆️
src/parser/expression.js	97.38% <100%> (ø)	⬆️

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