Add tests for uncovered cases

[dbwiddis]

Description

Adds tests for most of the uncovered lines.

$ poetry run coverage report
Name                                                                     Stmts   Miss  Cover
--------------------------------------------------------------------------------------------
TOTAL                                                                     2233     31    99%

(To be fair, that report includes test lines, so it's not quite that good. 🤷 )

From the CI test: codecov/project — 93.44% (+1.90%) compared to c31b5b8

Misses are:

• internal handler classes not yet implemented (10 lines), ignoring for now
• auto-generated protobuf files (8 lines) (See Handling auto-generated protobuf files #23)
• setters on outbound message that I'm not sure how to test (please help)
• pass on an abstract method (can't test)
• in StreamInput.read_array_size(), the size is read as a v_int which cannot be negative, so the exception on negative array size branch of code is unreachable (the test is there to catch integer overflow in Java, should it be removed?)
• No test of InvalidTraceDataFormat in the netty tests all based on valid logs (why are we including test files in test coverage?)

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[codecov]

Codecov Report

Merging #24 (14343b4) into main (c31b5b8) will increase coverage by 1.90%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main      #24      +/-   ##
==========================================
+ Coverage   91.53%   93.44%   +1.90%     
==========================================
  Files          43       43              
  Lines        1205     1205              
==========================================
+ Hits         1103     1126      +23     
+ Misses        102       79      -23     

see 14 files with indirect coverage changes