Pass empty function as callback for fs.unlink calls

Signed-off-by: Lauri Nevala <lauri.nevala@gmail.com>

src/main/kubectl.ts

@@ -205,7 +205,7 @@ export class Kubectl {
       })
       stream.on("error", (error) => {
         logger.error(error)
-        fs.unlink(this.path, null)
+        fs.unlink(this.path, () => {})
         reject(error)
       })
       file.on("close", () => {

src/main/lens-binary.ts

@@ -164,7 +164,7 @@ export class LensBinary {
 
     stream.on("error", (error) => {
       logger.error(error)
-      fs.unlink(binaryPath, null)
+      fs.unlink(binaryPath, () => {})
       throw(error)
     })
     return new Promise((resolve, reject) => {