json-rpc: Give `waitblockheight` an error code for timeouts

We need to differentiate timeouts from other results, so make it recognizable.

common/jsonrpc_errors.h

@@ -84,4 +84,7 @@ static const errcode_t OFFER_EXPIRED = 1002;
 static const errcode_t OFFER_ROUTE_NOT_FOUND = 1003;
 static const errcode_t OFFER_BAD_INVREQ_REPLY = 1004;
 
+/* Errors from wait* commands */
+static const errcode_t WAIT_TIMEOUT = 2000;
+
 #endif /* LIGHTNING_COMMON_JSONRPC_ERRORS_H */

doc/lightning-waitblockheight.7

@@ -23,7 +23,7 @@ the block height at the time the command returns\.
 
 
 If \fItimeout\fR seconds is reached without the specified blockheight
-being reached, this command will fail\.
+being reached, this command will fail with a code of \fB2000\fR\.
 
 .SH AUTHOR
 
@@ -33,4 +33,4 @@ ZmnSCPxj \fI<ZmnSCPxj@protonmail.com\fR> is mainly responsible\.
 
 Main web site: \fIhttps://github.com/ElementsProject/lightning\fR
 
-\" SHA256STAMP:5714e6333e5ba57cc00de425e6dc411f2c30812bbc8d95d01d50c460ee002e29
+\" SHA256STAMP:ac3320b4b9e679d8c407e42c9663540e2fc2aca75143d192f58ce255ca9b3700

doc/lightning-waitblockheight.7.md

@@ -24,7 +24,7 @@ an object with the single field *blockheight* is returned, which is
 the block height at the time the command returns.
 
 If *timeout* seconds is reached without the specified blockheight
-being reached, this command will fail.
+being reached, this command will fail with a code of `2000`.
 
 AUTHOR
 ------

lightningd/peer_control.c

@@ -1850,7 +1850,7 @@ timeout_waitblockheight_waiter(struct waitblockheight_waiter *w)
 	list_del(&w->list);
 	w->removed = true;
 	tal_steal(tmpctx, w);
-	was_pending(command_fail(w->cmd, LIGHTNINGD,
+	was_pending(command_fail(w->cmd, WAIT_TIMEOUT,
 				 "Timed out."));
 }
 /* Called by lightningd at each new block.  */