Maintenance by design
There are many times when I see this type of question regarding maintainability of the code. The line between code maintenance and user friendly becomes blurred. This is most evident when the coder is also the end user, the interface UI is misunderstood by familiarity of use, it is of course the IDE. This may sound somewhat pedantic, ...
There are few things that can be improved, will start with the major ones:
Instead of having function for each API call you can generalise it a bit like so:
/* Updated the name, since it's not only for transactions anymore
Since we no longer know the exact endpoint we will have to pass it to the function
I would also add `requestMeta` parameter ...
Not a full review, but several issues pop up at a quick scan:
Avoid panic, it's meant for reporting a bug in the program (e.g. dividing by zero, failing a bounds check, dereferencing a nil pointer, etc) and not for user errors (e.g. a failure to complete an HTTP request).
Panics also produce stack traces by default. Users should (almost) never get shown ...