Fix for error message when reloading iOS application during build (#25)

Description: 
This is a primitive fix of a problem with reloading on iOS during build.

Before: 
When reloading when subprocess running `xcodebuild` was active the
information about that process being killed would leak and cause change
in `ProjectState.status` to `buildError` despite the fact that new build
was up and running.

After: this change prevents unwanted change in status, when it is caused
by previous session

Fixes: #8

---------

Co-authored-by: Filip Andrzej Kaminski <[email protected]>

packages/vscode-extension/src/project/project.ts

@@ -321,8 +321,9 @@ export class Project implements Disposable, MetroDelegate, ProjectInterface {
     extensionContext.workspaceState.update(LAST_SELECTED_DEVICE_KEY, deviceInfo.id);
 
     this.reloadingMetro = false;
-    this.deviceSession?.dispose();
+    const prevSession = this.deviceSession;
     this.deviceSession = undefined;
+    prevSession?.dispose();
 
     this.updateProjectState({
       selectedDevice: deviceInfo,
@@ -331,6 +332,8 @@ export class Project implements Disposable, MetroDelegate, ProjectInterface {
       previewURL: undefined,
     });
 
+    let newDeviceSession;
+
     try {
       const device = await this.deviceManager.getDevice(deviceInfo);
       Logger.debug("Selected device is ready");
@@ -340,7 +343,7 @@ export class Project implements Disposable, MetroDelegate, ProjectInterface {
       // wait for metro/devtools to start before we continue
       await Promise.all([this.metro.ready(), this.devtools.ready()]);
       Logger.debug("Metro & devtools ready");
-      const newDeviceSession = new DeviceSession(
+      newDeviceSession = new DeviceSession(
         device,
         this.devtools,
         this.metro,
@@ -370,7 +373,10 @@ export class Project implements Disposable, MetroDelegate, ProjectInterface {
       });
     } catch (e) {
       Logger.error("Couldn't start device session", e);
-      if (this.projectState.selectedDevice === deviceInfo) {
+      if (
+        this.projectState.selectedDevice === deviceInfo &&
+        this.deviceSession === newDeviceSession
+      ) {
         this.updateProjectState({
           status: "buildError",
         });