Fix intellij-rust#3764 possible NPE in VFS batch (macro expansion)

I don't sure what exactly causes this NPS, but I added more
validity checks, so it should help

Author: vlad20012

src/191/main/kotlin/org/rust/lang/core/macros/MacroExpansionVfsBatch.kt

@@ -32,8 +32,9 @@ private class EventBasedVfsBatch191 : EventBasedVfsBatch() {
             VFileContentChangeEvent(null, vFile, vFile.modificationStamp, -1, true)
         }
         is Event.Delete -> {
-            val vFile = LocalFileSystem.getInstance().findFileByPath(file.toString())!!
-            VFileDeleteEvent(null, vFile, true)
+            val vFile = LocalFileSystem.getInstance().findFileByPath(file.toString())
+            // skip if file is already deleted (not sure how this can happen)
+            if (vFile == null) null else VFileDeleteEvent(null, vFile, true)
         }
     }
 }

src/main/kotlin/org/rust/lang/core/macros/ExpandedMacroStorage.kt

@@ -498,7 +498,7 @@ class ExpandedMacroInfo(
     val callHash: HashCode?,
     var stubIndex: Int = -1
 ) {
-    val expansionFileUrl: String? get() = expansionFile?.url
+    private val expansionFileUrl: String? get() = expansionFile?.url
     val fileId: Int get() = expansionFile?.fileId ?: -1
 
     @Volatile

src/main/kotlin/org/rust/lang/core/macros/MacroExpansionManager.kt

@@ -309,7 +309,7 @@ private class MacroExpansionServiceImplInner(
                 val toRemove = mutableListOf<ExpandedMacroInfo>()
                 runReadAction {
                     storage.processExpandedMacroInfos { info ->
-                        if (info.expansionFileUrl != null && info.expansionFile?.isValid != true) {
+                        if (info.expansionFile != null && !info.expansionFile.isValid) {
                             toRemove.add(info)
                         }
                     }

src/main/kotlin/org/rust/lang/core/macros/MacroExpansionTask.kt

@@ -266,7 +266,10 @@ object InvalidationPipeline {
 
     class Stage2(val info: ExpandedMacroInfo) : Pipeline.Stage2WriteToFs {
         override fun writeExpansionToFs(fs: MacroExpansionVfsBatch): Pipeline.Stage3SaveToStorage {
-            info.expansionFile?.let { fs.deleteFile(fs.resolve(it)) }
+            val expansionFile = info.expansionFile
+            if (expansionFile != null && expansionFile.isValid) {
+                fs.deleteFile(fs.resolve(expansionFile))
+            }
             return Stage3(info)
         }
     }
@@ -344,7 +347,9 @@ object ExpansionPipeline {
     ) : Pipeline.Stage2WriteToFs {
         override fun writeExpansionToFs(fs: MacroExpansionVfsBatch): Pipeline.Stage3SaveToStorage {
             val oldExpansionFile = info.expansionFile
-            oldExpansionFile?.let { fs.deleteFile(fs.resolve(it)) }
+            if (oldExpansionFile != null && oldExpansionFile.isValid) {
+                fs.deleteFile(fs.resolve(oldExpansionFile))
+            }
             return Stage3(call, info, def, null)
         }
     }

src/main/kotlin/org/rust/lang/core/macros/MacroExpansionVfsBatch.kt

@@ -158,7 +158,7 @@ abstract class EventBasedVfsBatch : VfsBatch() {
         manager.fireBeforeRefreshStart(/*asynchronous = */ false)
         try {
             val events = mutableListOf<VFileEvent>()
-            while (!dirEvents.isEmpty()) {
+            while (dirEvents.isNotEmpty()) {
                 val iter = dirEvents.iterator()
                 while (iter.hasNext()) {
                     val event = iter.next().toVFileEvent()
@@ -173,7 +173,7 @@ abstract class EventBasedVfsBatch : VfsBatch() {
             }
 
             if (fileEvents.isNotEmpty()) {
-                PersistentFS.getInstance().processEvents(fileEvents.map { it.toVFileEvent()!! })
+                PersistentFS.getInstance().processEvents(fileEvents.mapNotNull { it.toVFileEvent() })
                 fileEvents.clear()
             }
         } finally {