Prevent endless processing of problem pending events

If some pending event processing caused exception in PerModulePackageCacheService,
log the problem and consider event processed. Otherwise it is going to
be stuck there forever.

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/PerModulePackageCacheService.kt

@@ -11,11 +11,13 @@ import com.intellij.openapi.components.ServiceManager
 import com.intellij.openapi.diagnostic.Logger
 import com.intellij.openapi.fileTypes.FileTypeRegistry
 import com.intellij.openapi.module.Module
+import com.intellij.openapi.progress.ProcessCanceledException
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.project.rootManager
 import com.intellij.openapi.roots.ModuleRootEvent
 import com.intellij.openapi.roots.ModuleRootListener
 import com.intellij.openapi.util.Disposer
+import com.intellij.openapi.vfs.InvalidVirtualFileAccessException
 import com.intellij.openapi.vfs.VfsUtilCore
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.openapi.vfs.VirtualFileManager
@@ -237,9 +239,8 @@ class PerModulePackageCacheService(private val project: Project) {
         if (pendingVFileChanges.size + pendingKtFileChanges.size >= FULL_DROP_THRESHOLD) {
             onTooComplexChange()
         } else {
-
+            pendingVFileChanges.processPending { event ->
-            pendingVFileChanges.forEach { event ->
+                val vfile = event.file ?: return@processPending
-                val vfile = event.file ?: return@forEach
                 // When VirtualFile !isValid (deleted for example), it impossible to use getModuleInfoByVirtualFile
                 // For directory we must check both is it in some sourceRoot, and is it contains some sourceRoot
                 if (vfile.isDirectory || !vfile.isValid) {
@@ -256,18 +257,32 @@ class PerModulePackageCacheService(private val project: Project) {
                         invalidateCacheForModuleSourceInfo(it)
                     }
                 }
+
                 implicitPackagePrefixCache.update(event)
             }
-            pendingVFileChanges.clear()
 
-            pendingKtFileChanges.forEach { file ->
+            pendingKtFileChanges.processPending { file ->
                 if (file.virtualFile != null && file.virtualFile !in projectScope) {
-                    return@forEach
+                    return@processPending
                 }
                 (file.getNullableModuleInfo() as? ModuleSourceInfo)?.let { invalidateCacheForModuleSourceInfo(it) }
                 implicitPackagePrefixCache.update(file)
             }
-            pendingKtFileChanges.clear()
+        }
+    }
+
+    private inline fun <T> MutableCollection<T>.processPending(crossinline body: (T) -> Unit) {
+        this.removeIf { value ->
+            try {
+                body(value)
+            } catch (pce: ProcessCanceledException) {
+                throw pce
+            } catch (exc: Exception) {
+                // Log and proceed. Otherwise pending object processing won't be cleared and exception will be thrown forever.
+                LOG.error(exc)
+            }
+
+            return@removeIf true
         }
     }