Fix clippy warnings

[JohnnyMorganz]

No description provided.

[codecov]

Codecov Report

Merging #501 (411ac8b) into master (eb29c03) will not change coverage.
The diff coverage is 90.00%.

@@           Coverage Diff           @@
##           master     #501   +/-   ##
=======================================
  Coverage   97.66%   97.66%           
=======================================
  Files          14       14           
  Lines        5351     5351           
=======================================
  Hits         5226     5226           
  Misses        125      125           

Impacted Files	Coverage Δ
src/formatters/general.rs	96.66% <ø> (ø)
src/lib.rs	96.29% <80.00%> (ø)
src/context.rs	97.24% <100.00%> (ø)
src/formatters/expression.rs	97.09% <100.00%> (ø)

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[matthargett]

needs rustfmt, then looks good:

 --> src/formatters/functions.rs:878:13
    |
878 |             (),
    |             ^^ expected enum `std::option::Option`, found `()`
    |
    = note:   expected enum `std::option::Option<full_moon::ast::types::TypeSpecifier>`
            found unit type `()`