Prevent SIGSEGV when shutting down nimsuggest processes (#377)

* Add exe files to gitignore.

* Fix typo.

* Add a guard that prevents attempts to shut down non-existent processes.

Author: moigagoo

.gitignore

@@ -3,6 +3,7 @@
 nimcache/
 
 *.log
+*.exe
 tests/all
 /nimlangserver
 nimble.develop

lstransports.nim

@@ -246,7 +246,7 @@ proc startStdioLoop*(ls: LanguageServer): Future[void] {.async.} =
     freeShared(ls.stdinContext.value[0].addr)
     await ls.stdinContext.onMainReadSignal.fire()
     if msg == "":
-      error "Client discconected"
+      error "Client disconnected"
       break
     ls.processMessage(msg)
 

suggestapi.nim

@@ -268,7 +268,8 @@ proc markFailed(self: Project, errMessage: string) {.raises: [].} =
 
 proc stop*(self: Project) =
   debug "Stopping nimsuggest for ", root = self.file
-  asyncSpawn shutdownChildProcess(self.process)
+  if not self.process.isNil:
+    asyncSpawn shutdownChildProcess(self.process)
 
 proc doWithTimeout*[T](fut: Future[T], timeout: int, s: string): owned(Future[bool]) =
   var retFuture = newFuture[bool]("asyncdispatch.`doWithTimeout`")