Allows caller to set code and exact message to be returned.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: pyln-client: plugins can now raise RpcException for finer control over error returns.
We had a couple of instances where a plugin would be killed by `lightningd`
because we were returning a result of an exception twice, and it was hard to
trace down the logic error in the user plugin that caused that. This patch
adds a traceback the first time we return a result/exception, and raise an
exception with a stacktrace of the first termination when a second one comes
in.
This can still terminate the plugin, but the programmer gets a clear
indication where the result was set, and can potentially even recover from it.
Changelog-Added: pyln: Plugin method and hook requests prevent the plugin developer from accidentally setting the result multiple times, and will raise an exception detailing where the result was first set.
This should not affect any consumer of the API since we just shift the actual
implementation from one side to the other, and keep aliases in place so
scripts don't break.
We also bump the version number from 0.0.7.3 to 0.7.4 which allows us to be in
sync with c-lightning itself, and remove the superfluous `0` in front.
