fix(GUI): multiple JSON objects coming up at once from the IPC client

lib/src/child-writer/writer-proxy.js

@@ -157,7 +157,21 @@ return isElevated().then((elevated) => {
         child.on('close', resolve);
 
         const emitMessage = (data) => {
-          ipc.of[process.env.IPC_SERVER_ID].emit('message', data.toString());
+
+          // Output from stdout/stderr coming from the CLI might be buffered,
+          // causing several progress lines to come up at once as single message.
+          // Trying to parse multiple JSON objects separated by new lines will
+          // of course make the parser confused, causing errors later on.
+          //
+          // As a solution, we split the data coming in from the CLI into
+          // separate lines, and only emit a "message" event for the last one.
+          //
+          // Since each line is terminated by a new line, the last string
+          // is an empty string, which we don't want to send to the IPC
+          // server, so we take the last element of every element but the last.
+          const object = _.last(_.initial(_.split(data.toString(), /\r?\n/)));
+          ipc.of[process.env.IPC_SERVER_ID].emit('message', object);
+
         };
 
         child.stdout.on('data', emitMessage);