target: Throw error in 'debug_reason' command

Instead of returning an 'error string', throw an error. This makes it
much easier to handle errors in Tcl scripts or in tools that use Tcl RPC.

Change-Id: I75c48750cfad7430fa5e6bc88fe04ebd59d34cea
Signed-off-by: Marc Schink <[email protected]>
Reviewed-on: https://review.openocd.org/c/openocd/+/8006
Tested-by: jenkins
Reviewed-by: Antonio Borneo <[email protected]>

Author: zapb-0

src/target/target.c

@@ -5845,7 +5845,17 @@ COMMAND_HANDLER(handle_target_debug_reason)
 
 	struct target *target = get_current_target(CMD_CTX);
 
-	command_print(CMD, "%s", debug_reason_name(target));
+
+	const char *debug_reason = nvp_value2name(nvp_target_debug_reason,
+		target->debug_reason)->name;
+
+	if (!debug_reason) {
+		command_print(CMD, "bug: invalid debug reason (%d)",
+			target->debug_reason);
+		return ERROR_FAIL;
+	}
+
+	command_print(CMD, "%s", debug_reason);
 
 	return ERROR_OK;
 }