remove lastErr variables from rpc_test.go (hemilabs#185)

* remove lastErr variables from rpc_test.go

lastErr was added to handle for something that likely shouldn't have been; it's an un-needed way to handle for errors.  replace with simply failing the test if there are errors.

fixes hemilabs#182

* removed un-needed for loops

* bump test timeout

* re-added needed break

* surround break in else for readability

* tune timeout back to 1 minute

* lint

* Update service/tbc/rpc_test.go

Co-authored-by: Joshua Sing <[email protected]>

* Update service/tbc/rpc_test.go

Co-authored-by: Joshua Sing <[email protected]>

* cleanup from pr feedback

* fixed error checking based on feedback

* handle write errors differently in tests

* get rid of some shadowing

* more code cleanup

* fixed test

* trying larger wait

* fix byte order

* pr feedback

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Co-authored-by: Joshua Sing <[email protected]>