Use if let else in unit tests in parse

[JSAbrahams]

Summary

• Use let else construct in many unit tests
• Streamline format! macro calls.

[codecov[bot]]

Codecov Report

Merging #424 (9255fe2) into develop (9346f06) will decrease coverage by 0.01%. The diff coverage is 59.57%.

@@             Coverage Diff             @@
##           develop     #424      +/-   ##
===========================================
- Coverage    88.19%   88.17%   -0.02%     
===========================================
  Files          110      110              
  Lines        12042    12023      -19     
===========================================
- Hits         10620    10601      -19     
  Misses        1422     1422              

Impacted Files	Coverage Δ
src/parse/operation.rs	99.52% <ø> (ø)
src/parse/result.rs	43.13% <0.00%> (ø)
src/parse/call.rs	93.96% <50.00%> (-0.16%)	:arrow_down:
src/parse/control_flow_expr.rs	93.00% <55.55%> (-0.20%)	:arrow_down:
src/parse/collection.rs	86.71% <56.25%> (-0.63%)	:arrow_down:
src/parse/statement.rs	91.15% <66.66%> (-0.18%)	:arrow_down:
src/parse/expression.rs	94.73% <75.00%> (ø)
src/parse/expr_or_stmt.rs	93.95% <100.00%> (-0.07%)	:arrow_down: